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TABLE OF CONTENTSPage

MotionSpeed Reading 118Interpreting Distance vs. Time Graphs 120The Domino Effect 122Mr. Murry Review Pages 126Word Problem Primer 127Speed and Velocity Word Problems 128Changing Speeds 130Flying High Lab 132

MomentumMomentum Reading 134Momentum Review Questions 135Momentum Math I 136Momentum Math II 138

AccelerationAcceleration Reading 142Speed – Velocity Time Graphs 144Acceleration Math 146Acceleration, Velocity, and Momentum Lab 150

Newton’s LawsNewton’s Laws and Real Systems Reading 154Newton’s Laws Reading Questions 156Water, Water Everywhere Lab 158Crash Car Dummies Lab 160Newton’s Second Law Reading 164Newton’s Second Law Reading Questions 166Force Problems 168Newton’s Second Law Math – Weight 172Newton’s Third Law Reading 174Newton’s Third Law Reading Questions 176Calculating Net Force 178Newton’s Three Laws Review Mr. Murray 180Newton’s Car Lab Write Up 182Newton’s Laws of Motion Lab 184

116

Speed

Imagine three students walking down the hall. One is walking as fast as he can without getting in trouble. The other is walking somewhat more slowly than but not as slow as the last student. Which student is demonstrating speed? How would you define speed?

According to the scientific definition of speed, all three students demonstrated speed. Speed represents a rate or the amount of time it takes to cover a certain amount of distance. The actual scientific formula for speed is distance covered divided by the time or

or in shorthand, .

The standard unit for speed is meters per second (m/s) when distance is measured in meters and time is in seconds. Scientists sometimes find it more useful to define a new term that also includes the direction so that 60 mph south is different from 60 mph east. The new term is velocity. It is calculated just like speed, but if 25 mph east is considered to be a positive number, 25 mph west would be negative. Since speed and velocity are often the same, scientists get sloppy and use the words interchangeably.

So what do we mean when we say speed is relative? When we re reading in a car, the book does not appear to be moving at 50 or 60 mph, but that is because we are also moving at the same speed. When we see pictures in space of astronauts on spacewalks, everything seems to be moving very slowly. But, even though these objects are moving slowly relative to each other while in orbit, they are actually traveling about 17,500 mph. You and your desk (and the rest of the planet) are traveling around the sun at about 66,500 mph, as well.

118

distance

Did you know that the Atlantic Ocean is growing at about the same speed as your fingernails? Magma rises at the Mid-Atlantic Ridge and creates about 1 cm of new ocean floor each year. That’s approximately the length of fingernail you’ll trim off in a year. Sunlight takes about 8 minutes to travel from the sun to the earth. Light travels at 300,000 km/s in space. Notice, both these examples include both distance and time.

If an object travels equal distances in equal amounts of time it is traveling at a constant speed. Since a picture is worth a thousand words, we often show the relationship between speed and time using a graph like the one pictured below. Notice that the lines are all straight. This means each of the objects pictured in the graph travel the same distance each second which in turn means they are traveling at a constant speed. The lines slope upward which indicates that distance is increasing as time is increasing. They are moving away from the starting point.

If the store is 5 km from you house and it took you 10 minutes to get there, you traveled 5 km in 10 minutes. Your average speed is:

119

Interpreting Distance vs. Time Graphs

Consider the graph below.

1. It is made up of three line segments labeled A, B, and C. Which of the line segments represents an object moving away from the starting point?

2. Why?

3. Which line segment represents the object not moving?

4. Why?

5. What does the last line segment represent?

6. Which segment represents the object moving at the greatest speed?

7. Why?

8. What does the slope of the line represent?

9. How would the graph of a speed of 5 m/s look different from one of 15 m/s if the scale remained the same?

120

In your own words, describe the motion occurring in each of the graphs above.

Figure 1

Figure 2

Figure 3

Figure 4

121

The Domino Effect

Purpose To investigate the ways in which distance, time and average speed are

interrelated by maximizing the speed of falling dominoes. To become familiar with elementary graphing techniques.

Required Equipment/SuppliesApproximately 50 dominoesStopwatchMeterstick

DiscussionA central property of motion is speed – the rate at which distance is covered. By rate, we mean how much or how many of something per unit of time: how many raindrops hitting a roof in a minute, how much interest earned on a bank account in year. When we measure the speed of an automobile, we measure the rate at which this easily seen physical thing moves over the ground – for instance, how many kilometers per hour. But when we measure the speed of sound or the speed of light, we measure the rate at which energy moves. We cannot see this energy. We can, however, see and measure the speed of the energy pulse that makes a row of dominoes fall.

Procedure

Step 1: Set up 50 dominoes in a straight row, with equal spacing between the. The dominoes must be spaced at least the thickness of one domino apart. Your goal is to maximize the speed at which a row of dominoes falls down. Set the dominoes in a way you think will give the greatest speed.

Step 2: Measure the total length of your row of dominoes.

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Set up string of dominoes.

Step 3: Compute the average spacing distance between dominoes by measuring the length from the middle of the first domino to the middle of the last one, and divide this number by the number of domino spacings.

Average distance between dominoes = ___________________

Step 4 Measure the length of a domino.

Length of domino = ____________________________

Spacing distance = __________________ domino lengths

Step 5: Measure the time it takes for your row of dominoes to fall down.

Time = ___________________________

Step 6: Compute the average toppling speed for your row of dominoes.

Average speed = _________________________

Step 7: Repeat Steps 5 and 6 for at least three more spacings. Include a spacing that is about as small as you can make it and still produce toppling and a spacing that is about as large as you can make it and still produce toppling. Record you data (including data for the first trial in Data Table A.

Step 8: Using a separate piece of graph paper, make a graph of your data by sketching a smooth curve through your data points. Identify the point on the curve where the speed is a maximum or minimum (this need not be exactly one of your measured points).

TRIAL LENGTH AVERAGE SPACING

TIME SPEED

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Analysis

1. What is a definition of average speed?

2. What are the factors that affect the speed of falling dominoes?.

3. From your graph, what is the maximum or minimum toppling speed?

4. What spacing between dominoes do you predict would give the maximum or minimum speed? What is the ratio of this spacing to the length of a domino?

At the maximum or minimum toppling speed of the row of dominoes, how long a row of dominoes would be required to make a string that takes one minute to fall?

124

Speed and Velocity

It is the job of physics to explain why things happen. But the first task is to describe what happens. We are going to use algebra to write mathematical descriptions of the way things move. We must begin by defining our variables carefully. The formula for speed is distance divided by time and the units are meters per second.

Formulas: Abbreviations: Units:

Meters per second (m/s)

d = v x t meters (m)

seconds (s)

Example: Metal stakes are sometimes placed in glaciers to help measure a glacier’s movement. For several days in 1936, Alaska’s Black Rapids glacier surged as swiftly as 89 m per day down the valley. Find the glacier’s velocity in meters per second.

Formula and Work Set- Up

v = ?

d = 89 m

t = 1 day =

Ans: v = 1.0 x 10 -3 m/s down the valley

1. Find the velocity in meters per second of a runner who runs 100 m toward the finish line in 4.8 s.

Formula and Work Set- Upv =

d =

t =

Ans: ____________________

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distance

distance distance

2. Find the velocity of a baseball thrown 38 m from third base to first base in 1.7 s.Formula and Work Set- Up

v =

d =

t =

Ans: ____________________

3. If a car travels on Hwy 146 at 24 m/s, how far will the car go in 3600 s?Formula and Work Set- Up

v =

d =

t =

Ans: ____________________

4. 1If you travel southeast from one city to another city that is 31,400 m away and the trip takes 4 hours, what is your average velocity?


d =

t =

Ans: ____________________

5. The land speed record was broken with a velocity of 341.11 m/s. How long would it take to travel 4.5 km?


d =

t =

Ans: ____________________

130

MOMENTUMMovie sets use boulders made of foam rubber. These large foam “rocks” look just like real rocks, but you can throw them and catch them without hurting yourself or others. You can easily catch a foam rubber boulder because it has far less momentum than the real thing. Momentum is a property of a moving object that depends on its mass and velocity.

For an object moving in a straight line, momentum can be found by multiplying an object’s mass times its velocity, or

It’s important to remember that because momentum involves velocity, it includes an object’s direction. The momentum of an object is always in the same direction as its velocity. The SI units for momentum are kg∙m/s. Sometimes in science, when units get complicated like this, we “rename” them in honor of some scientist who did a lot of work in the area. However, the units for momentum have never been “renamed”. It is just the units for mass (kg) times the units for velocity (m/s).

A foam rubber boulder has less mass than a stone boulder, so it has less momentum as well. But since momentum also involves velocity, if the foam rubber boulder was going very fast, it could have equal momentum to the stone boulder if it was going super slowly. A bullet has only a little mass, but its extreme velocity gives it deadly momentum. The tectonic plates move mere centimeters per year. But even with that slow speed, they have tremendous momentum because of their mass.

We have not always understood the concept of momentum. Isaac Newton was the first one to develop it in the 1600’s. Since then many inventions have been designed using momentum (as well as other concepts). Your bike wheels are an example. We use the variable letter p in the formula for momentum. The shorthand form of it is

When one of Newton’s rivals was introduced to the concept of momentum, he exclaimed, “Now that’s progress.” The variable for momentum has been p ever since.

135

Name: Date: Period:

Momentum

Answer the following questions in complete sentences.

1. What is momentum?

2. What does velocity refer to?

3. How could the momentum of a replica equal the real thing?

4. What is the formula and units for momentum?

136

Momentum Math I

Momentum is a quantity defined as the product of an object's mass and its velocity. Momentum is affected by mass and velocity. If velocity is constant, and mass is increased, then momentum will be increased

Formula:Formulas: Abbreviations: Units:

p = m x v kilogram ∙ meters per second (kg∙m/s)

kilogram (g or kg)

meters per second (m/s)

Read each problem below and solve. Show the formula used and all work. This will count for 50% of the problem

1 .Calculate the momentum of a 75kg speed skater moving forward at 6m/sFormula and Work Set- Up

p =

m =

v =

Ans: ____________________

2. Calculate the momentum of a 135 kg ostrich running north at 16.2 m/sFormula and Work Set- Up

p =

m =

v =

Ans: ____________________

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3. Calculate the momentum of a 5.0 kg baby on a train moving eastward at 72 m/s.Formula and Work Set- Up

p=

m=

v =

Ans: ____________________

4. A pitcher in a professional baseball game throws a fastball, giving the baseball a momentum of 5.83 kg∙m/s. Given that the baseball has a mass of 0.145 kg what would be the velocity of the ball?

Formula and Work Set- Upp=

m=

v =

Ans: ____________________

5. The momentum of a baseball is 5.06 kg∙m/s away from home plate. The ball is moving with a velocity of 3.75 m/s. What is the mass the mass of the ball?

Formula and Work Set-Upp=

m=

v=

Ans: ____________________

6. The momentum of a jogger along the highway is 230 kg∙m/s northeast. He is traveling at a velocity of 2.65m/s. What is his mass?


m =

v =

Ans: ____________________

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Name Period

Momentum Math II1. A pitcher in a professional baseball game throws a fastball, giving the baseball a momentum of 5.83 kg∙m/s. Given that the baseball has a mass of 0.145 kg, what is its speed?


m =

v =

Ans: ____________________

2. The maximum speed measured for a golf ball is 273 km/h. If a golf ball with a mass of 47 g had a momentum of 5.83 kg∙m/s, the same of baseball in the previous problem, what would its speed be?


m =

v =

Ans: ____________________

3. The World Solar Challenge in 1987 was the first car race in which all the vehicles were solar powered. The winner was the GM Sunraycer, which had a mass of 177.4 kg, not counting the driver’s mass. Assume that the driver had a mass of 61.5 kg, so that the total momentum of the car and driver was 4,416 kg∙m/s. What was the car’s speed in m/s?


m =

v =

Ans: ____________________

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4. The lightest pilot-driven airplane ever built was the Baby Bird. Suppose the Baby Bird moves along the ground without a pilot at a speed of 88 km/h. Under these circumstances, the momentum of the empty plane would be only 2790 kgm/s. What is the mass of the plane?


m =

v =

Ans: ____________________

5. The most massive automobile to be manufactured on a regular bases was the Russian-made Zil-41047. If one of these cars were to move at just 8.9 m/s, its momentum would be 26,700 kgm/s. Use this information to calculate the mass of the Zil-41047,


m =

v =

Ans: ____________________

6. The Japanese high speed bullet train consists of 16 steel cars that have a combined mass of 25,000 kg. The top speed of the train is 61.1 m/s. What is the momentum of the train when traveling at top speed?


m =

v =

Ans: ____________________

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7. The current holder of the men’s world record for running 200 m is Michael Johnson who ran the race in just 19.32 seconds. Johnson’s mass at the time of his record-breaking run was about 77 kg. What was his momentum at that speed?


m =

v =

Ans: ____________________

8. The largest species of hummingbird is the Patagonia gigas, or giant hummingbird, of the Andes Mountains. The bird has a length of 21 cm and can fly with speeds up to 14 m/s. If the hummingbird’s momentum at top speed is 0.0278 kgm/s, what is its mass?


m =

v =

Ans: ____________________

9. A cheetah can run 274 m in 8.65 sec. If a cheetah with a mass of 50 kg is running at top speed, what is his momentum?


m =

v =

Ans: ____________________

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10. The fastest recorded speed for running the Indianapolis 500 was set in 1996. The minimum mass allowed in the race is 705 kg, so the momentum for the record-setting car would have been 74,900 kgm/s. What was the car’s speed?


m =

v =

Ans: ____________________

11. The fastest helicopter has a mass of 3343 kg and a maximum momentum of 372,300 kgm/s. What is the maximum speed of the helicopter?


m =

v =

Ans: ____________________

142

AccelerationThe next step in our study of force and motion is to examine acceleration. We will develop a highly sophisticated test for determining if acceleration has occurred. The test is called the “Big Drink Test”. Imagine that you have gone into a convenience store. In an attempt to get the best value possible, you have purchased a drink and filled it to the point of overflowing just like the one in the picture. Somehow you have been able to get into the passenger seat of a car without spilling any and the driver is about to start the car moving.

Even if you hold the drink as still as possible, what will happen to the drink if: The driver floors it? The driver steps on the breaks? The driver turns hard left? The driver turns hard right? The driver hit a deep pothole? The driver hits a large speed bump?

Anytime the drink would spill indicates acceleration.

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Acceleration is a change in velocity (speed or direction). In each case the speed or direction of the overfull drink changed. If the velocity of the cup changes, we know the cup is accelerating. Officially, the definition of acceleration is the change in speed divided by the time or

In shorthand,

The units for acceleration are slightly different than the units for velocity. Velocity (or speed) has units of m/s. Acceleration has units of m/s2. You have actually divided distance by time to get velocity, then divided by time again to get acceleration. That’s why the seconds in the denominator of the units is squared.

Just like with speed, a picture is worth a thousand words so we use a graph to represent a situation. This time the vertical (left) axis is not distance, but velocity. So if the graph rises, it is not representing an increasing distance, but an increasing speed. A graph of your car going from 0-60 mph in 5 seconds, then slowing down to a stop in the next 7 seconds would look something like this:

Note again, that the vertical axis is speed and not distance like before.What would traveling at a constant speed look like on the graph?

144

In your own words, describe the motion that is occurring in each of the graphs above.

Figure 1

Figure 2

Figure 3

Figure 4

145

Acceleration ProblemsFormula:


meters per second squared (m/s2)

1. What is the acceleration of a ball that starts from rest (0 m/s) and rolls down a ramp so that it is traveling 25 m/s 5 seconds later?


vi = vf =t = a =

Ans: = ______________

2. Johnny Hotfoot slams on the brakes of his car moving at 27 m/s and skids to a stop (0 m/s) in 4 seconds. What is his acceleration?


vi = vf =t = a =

Ans: = ______________

3. Kenny drops (0 m/s) his physics book off his aunt’s high-rise balcony. It hits the ground 1.5 seconds later traveling at a velocity of 11.25 m/s. What was the book’s acceleration?


vi = vf =t = a =

Ans: = ______________

147

Acceleration Calculations

Acceleration means a change in speed or direction. It can also be defined as a change in velocity per unit of time.



Calculate the acceleration of the following data.

Initial Velocity Final Velocity Time Acceleration

1. 0 km/hr 24 km/hr 3 s _______________

2. 0 m/s 35 m/s 5 s _______________

3. 20 km/hr 60 km/hr 10 s _______________

4. 50 m/s 150 m/s 5 s _______________

5. 25 km/hr 1200 km/hr 2 min _______________

6. A car accelerates from a standstill to 60 km/hr in 10 seconds. What is its acceleration? _______________

7. A car accelerates from 25 km/hr to 55 km/hr in 30 seconds. What is its acceleration? _______________

8 A train is accelerating at a rate of 0.81 m/s2. If Its initial velocity is 20 km/hr, what is its velocity after 30 seconds? ______________

9. A runner achieves a velocity of 11.1 m/s, 9 s after he begins. What is his acceleration? ______________

148

Acceleration Math

Acceleration is defined as the change in velocity divided by the change in time.


meters per second squared(m/s2)

meters per second (m/s)

seconds (s)

Please solve the following problems. Be sure to list all of your variables, formulas and show all your work.

1. Natalie accelerates her skateboard along a straight path from 0 m/s to 4.0 m/s in 2.5 s. Find her average acceleration.


vi = vf =t = a =

Ans: = ______________

2. A turtle swimming in a straight line toward shore has a speed of 0.50 m/s. After 4.0 s, its speed is 0.80 m/s. What is the turtle’s average acceleration?


vi = vf =t = a =

Ans: = ______________

149

3. Find the average acceleration of a northbound subway train that slows down from 12 m/s to 9.6 m/s in 0.8 s.

Formula and Work Set- Upvi = vf =t = a =

Ans: = ______________

4. Marisa’s car accelerates at tan average rate of 2.6 m/s2. Calculate how long it takes her car to accelerate from 24.6 m/s to 26.8 m/s.


Ans: = ______________

5. Simpson drives his car with an average velocity of 85 km/hr toward the east. How long will it take him to drive 560 km on a perfectly straight highway?


Ans: = ______________

6. How long will it take a cyclist with a forward acceleration of -0.5 m/s2 to bring a bicycle with an initial forward velocity of 13.5 m/s to a complete stop?


Ans: = ______________

150

Velocity, Acceleration, and Momentum

Problem: How does the shape of an object and air resistance affect the rate of free-fall of the object?

Background:

Speed is a term that means motion. Velocity is a term commonly used for speed. However, the use is incorrect because velocity implies both speed and direction. Hence, velocity is speed in a definite direction. The rate that the velocity changes is called acceleration. Acceleration can be a changing speed, a changing direction, or both. Galileo discovered that all bodies fall in the earth’s gravitational field with the same acceleration, if air resistance is not a factor. Air resistance (fluid friction) produces an upward force on a body so that its speed is limited. With air resistance, it follows that a point is eventually reached where a falling body will stop accelerating and fall at a constant speed. That constant speed is called terminal velocity.

Hypothesis: ______________________________________________

Materials: For each group:

Regular tennis ballTennis ball filled partially with small diameter shot (cut a slit in the ball, use a funnel to pour in a small amount of very fine shot)2 golf balls – different colorsOther assorted round, or nearly round objects to drop – Ex. Coins2 sheets plain printer paper

Procedure:

1. Create a Data Table to record results and observations.2. Drop the regular tennis ball and observe the time it takes to fall a set distance to

the floor.3. Drop each golf ball, individually, and compare how long it takes for the ball to

fall to the floor.4. Side by side, at the same time drop the regular ball and the shot—filled tennis

ball. Describe their time of fall.5. Drop a single piece of printer paper. Consider how long this piece of paper takes

to fall.6. Crush the piece of paper in your hand until it is a rounded clump about the same

size as the tennis ball, then drop this crushed piece of paper. Observe how the piece of paper drops to the floor. Consider how the time to fall has changed.

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Data Table:

Questions:1. Did the golf balls seem to fall at a different rate from the regular tennis ball?

2. Did the color of the golf ball make a difference in the time of fall?

3. When the balls were dropped side by side, how did their time of fall compare?

4. Does the mass of the object apparently affect the time of fall?

5. How did the single piece of paper fall to the ground?

6. What happened when the same piece of paper was crushed into a ball?

7. Why was there a difference in time of fall for the two pieces of paper?

152

Conclusion:

1. What factors determine how long it takes for an object to fall to the ground from a given height?

2. Write one paragraph that summaries your experiment and results. Include your acceptance or rejection of your hypothesis and why.

153

Name: Date: Period:

Newton’s Laws of Motion

Read the text pages and answer the following questions in complete sentences.

1. How did Galileo come up with the concept of inertia?

2. How does air hockey apply Newton’s first law of motion?

3. What does inertia mean?

157

Water, Water, Everywhere

Problem: How can you spin a cup of water around on a string and not have water come out of the cup?

Background:Centripetal force is a force is a force that tends to make bodies move towards the

center of rotation. It is why the planets tend to want to move in a straight line away from one another. However the force of attraction from gravity keeps them rotating around one another. The purpose of this exercise it to see if you can spin a cup fast enough to keep the water from coming out. The water wants to move in a straight line but the cup pushes on the water in a straight line.

Hypothesis:

Materials: 1 large Styrofoam cu1 piece of rope or cord, 6-7 feet longWater Clear area

Procedure:

1. Take a cup and poke 2 holes just a few centimeters from the top of the cup.2. Cut a piece of string about 1 m long and run it through the cup and tie it just

above the top of the cup.3. You should have most of the 1 m of string above the cup for you to hold on to.4. Fill the cup half full of water.5. Holding the string attached to the cup begin to swing the cup back and forth,

higher and higher, until you are able to make complete circles over your head. Continue to swing the cup around.

Questions/Conclusions

1. As you swing the cup what did you observe about the position of the water? Did the water remain parallel to the cup during the swing?

2. As you swing the cup higher and higher did the water come out of the cup?

159

3. Why or Why not?

4. Do you accept or reject your hypothesis? Why or Why not?

160

Name: Date: Period:

Crash Car Dummies

Problem: What variables measure an object’s inertia?

Background: Newton’s first law of motion states that an object at rest will remain at rest unless acted upon by an unbalanced force while an object in motion will remain in motion with constant speed and direction unless acted upon by an unbalanced force. Sometimes we forget that we are in motion while in a car even though we are jest sitting still. As the investigation will demonstrate, people will continue to stay in motion if the car stops.

Hypothesis: If _____________________________________________ then _________________________________________.

Materials: ClayCarriage carRampRing standRubber bandMeter stickStop (wall)

Procedure

1. Set one end of a ramp on the ring attached to the ring stand.

2. Place a stop at the bottom of the ramp.

3. Place a meter stick at the end of the ramp

4. Form three clay people of varying mass. The clay people will represent an adult, a teenager, and a baby.

5. Place one person in the car and let it roll down the ramp and crash into the wall (stop). Measure the distance the person flies out of the car over the wall. Record the distance in the data table. Record observations

6. Complete three trials with each person.

7. Secure one of the people in the car using a rubber band as a seat belt. Roll the car down the ramp and observe what happens.

8. Repeat step 7 with each person. Record observations

161

Data Table

Trail Distance Clay Flew (cm)

Observations

Baby

1

2

3

Seat beltTeen

1

2

3

Seat belt

Adult

1

2

3

Seat belt

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Analysis:

1. Describe Newton’s first law of motion?

2. What factors, beside mass, could have affected how far each passenger flew out of the car?

3. What is inertia and which person had the greatest inertia? How do you know?

4. Why did people fly out of the car?

5. What is the independent variable for this investigation?

6. What is the dependent variable for this investigation?

7. What variables are held constant in this investigation?

8. What could be done to the car to make the people fly out farther?

9. What is the relationship between mass and inertia?

10. When the seat belts were put on the passengers what happened to the people when the car hit the wall and stopped?

11. Why should the velocity of each car be the same at impact even if the mass is different?

12. Why did the mass differences of the baby, teen, and adult do little to affect the distance each flew out after the collision?

163

Conclusion:

Answer the conclusion questions in complete sentence. Explain fully.

1. How can you relate this investigation of Newton’s first law of motion to daily life when you wear seat belts in a car?

2. A friend does not wear his seat belt when in the car. From this investigation, how could you convince him of the importance of wearing seat belts?

3. How could you change the experiment so that the velocity of the impact changes?

164

Newton’s Second Law question

1. How does Newton’s second Law apply to golf?

2. State Newton’s second Law mathematically. Include the units.

3. What is the difference in mass and weight?

4. Explain why astronauts give the appearance of weightlessness.

167

ForceA force is a push or pull. To calculate force, we use the following formula:


Newtons (N)

Kilograms (kg)


Example: With what force will a rubber ball hit the ground if it has a mass of 0.25 kg?

Formula: F = maF = ? F = mam = 0.25 kg F = (0.25 kg)(9.8 m/s2)a = 9.8 m/s2 F = 2.45 N

1. What is the net force necessary for a 2.5 x 103 kg train to accelerate forward at 2.0 m/s2?

Formula and Work Set-UpF = m =

a =

Ans: _______________________

2. A tennis ball accelerates downward to 9.8 m/s2. If the gravitational force acting on the baseball is 2.8 N, what is the baseball’s mass?

Formula and Work Set-UpF = m =

a =

Ans: _______________________

169

3. A sailboat and its crew have a combined mass of 1200 kg. If the sailboat experiences unbalanced forces of 1500 N pushing it forward what is the sailboats acceleration?

Formula and Work Set-UpF =

m =

a =

Ans: = ______________

4. With what force does a car hit a tree if the car has a mass of 3000 kg and it is accelerating at a rate of 2 m/s2?

Formula and Work Set- UpF =

m =

a =

Ans: = ______________

5. A 10 kg bowling ball would require what force to accelerate it down an alleyway at a rate of 3 m/s2?


m =

a =

Ans: = ______________

6. What is the mass of a falling rock if it hits the ground with a force of 147 N?Formula and Work Set- Up

F =

m =

a =

Ans: = ______________

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7. What is the acceleration of a softball if it has a mass of 10.50 kg and hits the catcher’s glove with a force of 25 N?


m =

a =

Ans: = ______________

8. What is the mass of a truck if it is accelerating at a rate of 5 m/s2 and hits a parked car with a force of 14,000 N?


m =

a =

Ans: = ______________

171

Newton’s Second Law Math – Weight

Weight is a force of gravity pulling down on a mass. Weight can change based on location but mass cannot. Solve the following weight problems and show all of your work.


Newtons (N)

Kilograms (kg)


1. A girl has a mass of 50 kg on earth where the acceleration due to gravity is 9.8 m/s2. Calculate her weight.

Formula and Work Set- Upm =

g =

Fw =

Ans: = ______________

2. A rock on Pluto has a weight of 5000 N and a mass of 250 kg. What is the acceleration due to gravity on Pluto?


g =

Fw =

Ans: = ______________

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3. An astronaut weighs about 1000 N on earth lands on the moon. What is his mass? (acceleration due to gravity = 9.8 m/s2)


g =

Fw =

Ans: = ______________

4. Calculate your weight of a man who weighs 100 lbs. on Earth in Newton’s. To find mass take the weight and divide by 2.2. This will give you the mass in kg.


g =

Fw =

Ans: = ______________

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Newton’s third law

Suppose you try jumping from a canoe onto a dock. Your attempt to propel yourself forward with one foot while the other foot reaches out toward the dock backfires. Instead it propels the canoe away from the dock. You land in the water. Newton’s third law of motion is to blame for this embarrassing scene.

For every action force, there is an equal and opposite reaction force.

Your foot pushes back on the canoe to propel you forward. The canoe simultaneously pushes forward on your foot to propel itself backward. The force your foot exerts on the canoe is the action force; the force the canoe exerts on our foot is the reaction force.

Think about swimming. Your paddling pushes the water backward and the water pushes your forward.

The figure below shows how rockets take advantage of Newton’s third law for propulsion. Hydrogen and oxygen gases combine and combust. This sustained reaction forces gas from the back of the rocket. The rocket pushes the gases backward; the gases push the rocket forward.

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Newton’s Third Law Questions

Using the text reading answer the following questions in complete sentences.

1. State Newton’s Third Law of Motion.

2. Use Newton’s Third Law to explain how a rocket is propelled.

3. What happens when equal and opposite forces are applied to the same object? To different objects?

4. How does Newton’s Third Law apply to objects with different masses?

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Name: Date: Period

Newtonian Car Lab Write-up

Problem: How does Newton’s Laws apply to movement?

Introduction:

Examples of Newton’s Laws are all around us. Throwing a ball, a car moving away form a stop sign, the moon moving around the Earth, and dropping a science book on the floor all demonstrate aspects of those laws. In this activity, you will construct a vehicle and then explain how it work, using Newton’s Laws of Motion.

Hypothesis: If _________________________________ then ___________________

Materials:

1 Styrofoam Plate2 straws1 balloonScissorsTape

Procedure:

You are to build a vehicle which is propelled only by air. You may use part or all of the materials listed above. You have One (1) period in which to design and complete the construction of your vehicle. At the next class period, there will be a competition to determine which vehicle in the class travels the greatest distance. Good Luck!

Write the steps of your procedure. What did you do 1st, 2nd, 3rd, …?

1.

2.

3.

4.

5.

6.

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Data:Draw a diagram of your design

Conclusion:

Explain how or why your vehicle moves in terms of Newton’s Laws. State any concepts or laws which apply.

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Newton’s Laws of MotionLab

INTRODUCTION:In this laboratory activity, students will investigate Newton’s three laws of motion.

PURPOSE:To demonstrate Newton’s Laws of Motion.

MATERIALS: Playing card 250 mL beaker Plastic straw Balloon Penny Petri dish containing 20 beads of 2 different masses 25 ft piece of string or twine Tape

PROCEDURE: PART A NEWTON’S FIRST LAW

1. Place a playing card on top of an empty beaker.

2. Place a penny on top of the card.

3. Flick the card sideways rapidly with your finger.

What happens to the card? ________________________________________________

What happens to the penny? _______________________________________________

Newton’s First Law says that an object at rest tends to remain at rest, while an object in motion tends to remain in motion – unless acted upon by some outside force.

What “outside” force was applied to the card? _________________________________.

Explain what happened to the penny, based on Newton’s First Law. ________________

What force acted on the penny to cause it to fall into the beaker? ___________________

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PROCEDURE PART B NEWTON’S SECOND LAW

1. Obtain a Petri dish containing small beads of different masses.

2. With the Petri dish lying on the lab table, slide it back and forth rapidly. Note the motion of the beads.

3. Is your hand supplying about the same amount of force to all of the beads in the Petri dish? ____________

4. Are all of the beads moving at the same speed? ___________________

5. Which is moving faster (on the average), the smaller beads or the larger ones? ________________________

6. Which beads, therefore, are harder to accelerate? ______________________-

Newton’s Seconds Law says that acceleration is equal to the net force acting on the object divided by the mass of the object: a = F/m

Therefore, if force stays the same, mass and acceleration are “inversely proportional”. In other words, as the mass of an object or particle goes up, its acceleration goes down (and vice versa)

Explain the motion of the beads in the Petri dish using Newton’s Second Law.

PROCEDURE: PART C NEWTON’S THIRD LAW

1. Obtain a 25 ft piece of string or twine and pass one end through a plastic straw. Have two students take an end of the string and spread as far apart as they can.

2. Blow up a balloon, but DO NOT tie off the end. Tape the balloon to the bottom of the straw.

3. Release the balloon.4. What happened when the balloon was released? __________________________

Newton’s Third Law says that for every action, there is an equal and opposite reaction.

Explain what happened to the balloon in terms of Newton’s Third Law.

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