8th grade science staar review -...

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Review STAAR

8th grade science

Name ___________________________________________ Class _____________

Underline your strong TEKS and circle your weak TEKS:

8.6A Unbalanced Forces

8.6B Speed, Velocity, & Acceleration

8.6C Newton’s Laws

7.7A Work

6.8A Potential and Kinetic Energy

6.8C Speed

6.8D Graphing Motion

6.9C Energy Transformations


____________________

Reporting Category 2: Force, Motion and Energy Unbalanced Forces – 8.6A

A ________________ is a push or a pull in a specific direction.

The combination of all of the forces acting on an object is called ________________________.

Determine the net force (size and direction) for the following:

If the forces acting on a moving object are balanced, what will the object do?

If the forces acting on an object at rest are balanced, what will the object do?

If the forces acting on a moving object are unbalanced, what will the object do?

If the forces acting on an object at rest are unbalanced, what will the object do?

Force is measured in what units? _______________________________

Friction is a force. How does friction affect the speed of a moving object?

A submarine is traveling in the water at 8.5 m/s.

Suddenly the sub encounters a swiftly moving

current. If the current is flowing against the

submarine at 3.0 m/s how will the sub be affected?

2N 5N

Net force= _______________

Balanced or unbalanced?

2N 2N 5N 5N

Net force= _______________


Net force= _______________


8.5 m/s 3.0 m/s


A diagram of the forces being applied to a box is provided (below). If the net force acting

on the box is 10 N to the right, what is the magnitude of the force applied by the boy

pulling to the left? Record your answer in the grid below. Show all work!

Which of the following objects requires the greatest amount of force to produce the

acceleration shown?

A student applies 2 Newtons of force to a toy car causing it to accelerate at a rate of 10

m/s2. What is the mass of the toy car in kg? Record your answer in the grid below. Show all work!

Object Acceleration

(m/s2) Mass (kg)

Object A 2.5 5

Object B 1.2 7

Object C 4.9 3

Object D 0.7 14


Speed, Velocity, & Acceleration – 8.6B

What is speed?

Average speed = ___________________________________ ÷ _________________________________

What is velocity?

What is acceleration?

Identify each of the examples as either a speed (S), velocity (V), or acceleration (A).

A car travels 2.5 hours in a northerly direction for 300 km. Determine the car’s speed and

velocity. Show all work!

Speed = _________________________

Velocity = ______________________________

Study the diagram below. A student rides a bike

2 hours from school to home, making stops along

the way. What is the average speed that the

student is traveling?

Did the student accelerate during the ride

home?

A rollercoaster slows as it travels up a hill.

A cyclist travels 40 kilometers in 2 hours.

A flock of geese flies north at 55 mph.

A racecar makes a slight left turn while maintaining the same speed.

An athlete can run about 12.5 km/hr.

friend’s house

4 km

3 km

2 km

school

library

home


Newton’s Laws – 8.6C

Newton’s _________ Law of Motion states that for every action, there is an equal and

opposite reaction. Forces come in pairs. It is often referred to as the law of action-reaction.

Newton’s _________ Law of Motion states that an object at rest will stay at rest and an

object in motion will stay in motion at the same speed and in the same direction unless

acted up by an unbalanced force. It is sometimes called the law of inertia.

Newton’s _________ Law of Motion states that an object acted upon by an unbalanced

force will accelerate in the direction of that force, in direct proportion to the strength of the

force, and in inverse proportion to the mass of the object. It is called the law of force and

acceleration.

Define inertia and give an example.

What formula is used for Newton’s Second Law of Motion? State the 3 forms of the formula.

Check One

First Law of Motion Second Law of Motion Third Law of Motion


If a team pulls with a combined force of 9000 N on an

airplane with a mass of 30,000 kg, what is the acceleration

of the airplane in m/s2? Record your answer in the grid

below. Show all work!

The shopping carts shown above are pushed down the hallway with the same amount of

force. Which cart has the greatest change in speed? Circle the cart above and explain

your answer below.

Work – 7.7A

In science, for “work” to be performed, a force must be used to move an object.

Regardless of how much force is being used, if no movement occurs, no work is done.

Work = _______________________________ x ___________________________________

Work is measured in a unit called _______________________________ ( _____ ).

The man in the picture is pushing against the beach ball with 20

Newtons of force. The ball does not move. How much work is

he doing? Show all work!

tennis racket and ball m = 1.0 kg

2 bowling balls m = 25 kg

variety of sport balls m = 12 kg


Use the information and diagrams below to answer the 2 questions that follow.

A student needs to lift a heavy ball up onto a table that is 2 meters high. She uses 6 N of

force to raise the ball straight up (Ex. #1), but only 3 Newtons of force is required to roll the

ball up the ramp (Ex. #2).

Calculate the amount of work done for each example above. Show all work!

Does the amount of work change in the two examples? Explain.

Which of the following results in the least amount of work being done?

A. A dog carries a toy 2 m with a force of 1 N.

B. A child moves a ball 3 m with a force of 4 N.

C. A student pushes a book with a force of 5 N for 1 m.

D. A coyote drags its prey with a force of 20 N for a distance of 5 m.

Potential and Kinetic Energy – 6.8A

Fill in the data table (right) to correctly classify the activities of the

children in the picture as either kinetic (K) or potential (P) energy.

2 m

F = 6 N

2 m

d = 4 m

F = 3 N

Example #1 Example #2

Exam

ple #1 w

ork Ex

am

ple

#2 w

ork

Activity Observed Classification

Girl jumping rope

Boy standing with

a soccer ball

Kite flying in the

wind

Boy balancing on

his head

Bee buzzing

around a boy’s

head


At which point does the water in the waterfall (left) have the

greatest gravitational potential energy? Circle your answer in

the picture.

Use the diagram of the rollercoaster above to fill in the missing information.

a) As the rollercoaster moves from point Z to point Y, the potential energy

______________________ as the kinetic energy ______________________.

b) As the rollercoaster moves from point Y to point X, the potential energy

______________________ as the kinetic energy ______________________.

c) At which of the 4 points does the cart have the least potential energy?

______________________

A diagram of a pendulum is shown to the left. The pendulum is

released from Position 1. At which two positions will the

pendulum’s potential energy equal its kinetic energy?

A. 1 and 2

B. 2 and 4

C. 3 and 4

D. 4 and 5

____________________________________ is energy that is stored and available to be used later.

____________________________________ is energy that an object has because of its motion.

1

2

3

4


Speed – 6.8C

If an object travels 42 meters in 6 seconds, what is its average speed?

A. 6 m/s

B. 7 m/s

C. 48 m/s

D. 252 m/s

What is the difference in average speed between two cars, one that traveled 150

kilometers in 5 hours and the other that traveled 130 kilometers in the same time? Record

and bubble in your answer below. Show all work!

Graphing Motion – 6.8D

In the graph to the right, how many kilometers has the

object moved after 10 minutes? _____________________

In the graph to the right, how many kilometers has the

object moved after 20 minutes? _____________________

In the graph to the right, how many minutes did it take

for the object to move 3.5 kilometers? ________________

Which of the following situations could be represented

by this graph?

A. A boy walks 1.5 km to the park in 10 minutes. Then he walks backwards to his house

in 10 minutes. Then he runs to his friend’s house which is 2 km away in 20 minutes.

B. A boy walks 10 kilometers to the park for 1.5 minutes. Then, he stops for a 10 minute

rest. After that, he continues on 2 km, which takes him 20 minutes.

C. A boy walks 1.5 km to the park in 10 minutes. He stops for a 10 minute rest before

continuing onto the store which is 2 km away from the park. It takes him 20 minutes to

get from the park to the store.

D. A boy walks 1.5 km to the park in 5 minutes. He stops for a 5 minute rest before

continuing onto the store which is 20 km away from the park. It takes him 40 minutes to

get from the park to the store.


Which graph shows the fastest speed? Circle your answer.

The graph below shows the speed of a car traveling north over a 16 second time period.

Based on the information in the graph, it can be concluded that in the first 8 seconds, the

car is -

A. changing its direction.

B. accelerating at a constant rate.

C. climbing a steep incline.

D. experiencing less and less friction.

Energy Transformations – 6.9C

Identify each of the 7 different forms of energy represented below. Label them using the

following terms: mechanical, chemical, thermal, electrical, light (or EM energy), sound, and

nuclear.

________________ ________________ ________________ ________________ ________________

_____________ ________________ _______________ _______________ ________________ _______________


_____________________________________ states that energy cannot be created or destroyed,

but only transformed into different forms.

Complete the chart using these types of energy: mechanical, thermal, electrical, light,

sound, chemical.

Beginning Energy Type

Type(s) of Energy

Converted To

Hair dryer

Battery Operated Radio

Glow stick

Piano

Plant going through photosynthesis

Roller coaster

Flashlight

8th grade science staar review -...

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