Motion and Point of Reference

• Motion is a ___________in _____________.

• Determining whether or not something has changed its position depends on your ___________ __ _______________.

• Your point of reference is where ____ are relative to the moving object.

Speed

Speed is the _____________ that indicates how much

_______________ you traveled divided by the amount of _________

that you traveled. It is measured in meters per second (m/s).

Formula = distance (meters) time (seconds)

Example:You ran the 100 m dash in 20 seconds100 m20 s = 5 m/s (you traveled 5 meters every second you were running)

Velocity• Velocity is the exact same formula as

_____________, but it has one big difference. VELOCITY IS THE ____________ PLUS THE ______________ YOU ARE TRAVELING.

• Use the example from before:You ran the 100 m dash in 20 seconds100 m20 s = 5 m/s W (you traveled 5 meter per second in a

western direction)

_________Speed vs. _________Speed

• Most of the time we calculate __________ speed (example: going to Grandma’s house).

• However, in some cases, an object travels at

a __________ rate when the speed never changes (do you have cruise control on your car?)

Graphing Average Speed

• Suppose Grandma lived 240 miles away, and you traveled there in 4 hours. Your car traveled at different ___________________ (different speeds in different directions), and you made a few stops along the way. So your graph would not be a perfectly _________________ ____________.

Constant Speed

• If you traveled at a _________________ speed of 60 mph, then a constant speed would be graphed as a ______________ line.

Acceleration

• Most people think of acceleration as speeding up, but acceleration is actually a _____________ ____ _______________ over time.

Formula:Final Velocity – Starting Velocity

Time (sec) Unit is m/s2 Or m/s/s

Acceleration

• Acceleration can occur when

1) You are ____________________ your speed (positive acceleration)

2) You are ____________________your speed (negative acceleration or deceleration)

3) You are _____________ __________________.

Acceleration Problems• You start off riding your bike at 5 m/s. Then you go

down a big hill. At the bottom of the hill your are traveling at 15 m/s. It took you 5 seconds to go from the top of the hill to the bottom of the hill

• 1) What was your rate of acceleration?

• 2) Was it positive or negative acceleration?

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Acceleration Problems• You are riding your bike at 20 m/s. You now are having to

go uphill. You don’t exert more effort, so, by the time you reach the top of the hill, you are traveling at 10 m/s. It took you 10 seconds to go from the bottom of the hill to the top.

• 1) Is this positive or negative acceleration?

• 2) what was your rate of acceleration?

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Momentum

• ______________is really a measure of how difficult it is to _________

a moving object.

• An object that collides with an object at rest (and bounces off )will

have the ________ momentum as it had before.

• An object that collides with an object in motion will experience a

momentum that is a ________________of both moving objects.

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Momentum Formulas

• Momentum equals the ________ of an object times its

___________: p (momentum) = mv

• So an 20 kg object traveling at 100 m/s W:P(force) = 20 kg x 100 m/s west = 2000kg/m/s west

If p = m x v, How would you find either mass or velocity (if you had force?) You would divide either into the force (P)

M = p/v or V = p/m

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Inertia

• Newton’s First Law of Motion proves that objects do not move or stop moving unless there are greater (______________) forces acting upon them. Inertia is the object’s tendency to either keep moving or not moving. A force that changes this has to be strong enough to change an object’s inertia.

Speed Problems

1) A family traveled a total of 480 miles in 12 hours. What was their average speed?

2) Myra ran for 10 seconds, and her average speed was 6 m/s. How far did she run?

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Acceleration Problems

1) Sam rode brother ‘s Big Wheel He started off traveling at 2 m/s. By the time Sam broke the toy, he had traveled for 4 s at 10 m/s. What was Sam’s rate of acceleration?

2) A train arrives at a station traveling at 10 miles per hour. 30 minutes ago it was traveling at 40 miles per hour. What was the train’s rate of acceleration?

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Acceleration Problem 3) An airplane’s rate of acceleration is 50 m/s2. The starting speed was

100 m/s. After a while the plane was traveling at 200 m/s. How long did it take the plane to accelerate?

4) An object with a mass of 50 kg is traveling at 14 m/s east. What is the force of this object?

5) An object thrown from a bridge has a force of 500g/m/s down. It has a mass of 125 g. What is the velocity of this object?

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Momentum Problems6) An object with a mass of 50 kg is traveling at

14 m/s east. What is the force of this object?

7) An object thrown from a bridge has a force of 500g/m/s down. It has a mass of 125 g. What is the velocity of this object?