MCAS Motion and Forces 2

1.

1 point

The diagram below shows an object traveling at a constant speed in a circular path.

Which labeled arrow represents the centripetal force acting on the object?

W

X

Y

Z

2.

1 point

The graph below represents the motion of a car as it moves along a straight road for 20 s.

Which statement best describes the motion of the car over the 20 s?

The car is initially at rest and then backs up for 10 s.

The car moves 20 m in the first 10 s and then stops.

The car travels at a constant speed for 10 s and then decelerates until it stops.

The car travels at a constant speed of 20 m/s and then decelerates until it is traveling at a constant speed of 15 m/s.

3.

1 point

A crate is being pulled along a floor by means of two ropes. A frictional force opposes the motion of the crate. The diagram below shows these three forces acting on the crate.

What is the magnitude of the net force acting on the crate?

800 N

1000 N

1400 N

2000 N

4.

1 point

A car is moving at 25 m/s north. Which of the following is a vector quantity?

the speed of the car

the velocity of the car

the potential energy of the car

the distance traveled by the car

5.

1 point

The diagram below shows a comet in an elliptical orbit around a star.

Which arrow indicates the direction of the gravitational force the star exerts on the comet when the comet is in the position shown?

1

2

3

4

6.

1 point

A student leaving school walks 2.5 km north and then walks 1.0 km south. What is the student’s displacement?

1.0 km south

1.5 km north

2.5 km north

3.5 km south

7.

1 point

A student pushes a book across a classroom table. Which of the following statements best explains the difference between the amount of force needed to start the book moving and the amount of force needed to keep it moving?

Less force is needed to start the book moving, because there is less friction than when it is already moving.

Less force is needed to start the book moving, because there is less potential energy in the table than in the book.

More force is needed to start the book moving, because there is more potential energy in the table than in the book.

More force is needed to start the book moving, because there is more friction than when it is already moving.

8.

1 point

A racecar travels at an average speed of 80 m/s in a race. The total distance of the race is 640,000 m.
How long does it take the racecar to finish the race?

800 s

8,000 s

6,400,000 s

51,200,000 s

9.

1 point

A person with a weight of 120 lb. is standing on a scale.

What force is the scale exerting on the person?

0 lb. up

60 lb. up

120 lb. up

240 lb. up

10.

1 point

Two students are in-line skating. The diagram below shows student S pushing student T. Student S has a mass of 60 kg, and student T has a mass of 40 kg.

Student S is pushing student T in a straight line with a force equal to the friction on student T’s skates. Which of the following must happen if student S continues to push student T with the same force?

Student T will lose his balance.

Student T will travel in a circle.

Student T will move at a constant velocity.

Student T will move at a constant acceleration.

11.

1 point

A student is driving her car when an insect strikes her windshield. Which of the following statements best describes the forces in this situation?

The insect strikes the windshield with the same force as the windshield strikes the insect.

The insect strikes the windshield with a force, and the windshield exerts no force on the insect.

The insect exerts no force on the windshield, and the windshield strikes the insect with a large force.

The insect strikes the windshield with a small force, and the windshield strikes the insect with a large force.

12.

1 point

The graph below shows the distance an object traveled over time.

Which line segment represents the time interval during which the object was moving at a positive constant speed?

segment W

segment X

segment Y

segment Z

13.

1 point

Which of the following statements identifies the main difference between vector and scalar quantities?

Only vectors have direction.

Only scalars have magnitude.

Only scalars have units associated with them.

Only vectors have units associated with them.

14.

1 point

A boy has a ball on a string. He swings the ball in a circle above his head. The diagram below is a top view of this situation.

If the boy releases the string when the ball is at position R, at which point will the ball land?

point W

point X

point Y

point Z

15.

1 point

Four students push on a block of wood with the forces shown in the diagram below. Assume friction is negligible.

The block slides horizontally. What is the net force acting on the block of wood?

3 N to the left

8 N to the left

11 N to the right

25 N to the right

16.

1 point

An elevator in an office building completed the following trips:
1st floor to 8th floor
8th floor to 4th floor
4th floor to 13th floor
The distance between each floor of the office building is 3.0 m.
Which table shows the total distance traveled and displacement of the elevator?

17.

1 point

Which of the following statements best describes the force of Earth’s gravity on a rocket moving upward?

The gravitational force is constant for all altitudes.

The gravitational force is weaker when the rocket is higher.

The gravitational force is stronger when the rocket is higher.

The gravitational force is zero when the altitude is greater than 10,000 miles.

18.

1 point

A 2000 kg car is pulling a 1000 kg trailer. The car’s engine exerts a 6000 N force to move the car and the trailer. In addition, the car and the trailer each experience a 1000 N frictional force as they are being pulled, as represented below.

What is the magnitude of the net force on this system?

2000 N

4000 N

5000 N

8000 N

19.

1 point

Which of the following statements describes a result of Earth’s gravitational pull on the Moon?

The Moon has craters.

The Moon orbits around Earth.

The Moon lacks an atmosphere.

The Moon has less gravity than Earth.

20.

1 point

Two students are standing next to each other on a level field. One of the students throws a table tennis ball forward toward a line 2.0 m away. At the same time, the second student throws a bowling ball in the same direction. Both balls take the same time to travel the 2.0 m.
Only the second student feels a noticeable backward push when she throws her ball.
Which of the following statements explains why only the second student feels a noticeable backward push?

The bowling ball exerts a much larger reaction force.

The bowling ball undergoes a much larger acceleration.

The bowling ball requires more force to overcome gravity.

The bowling ball converts more inertia into kinetic energy.

21.

1 point

Which of the following will always change when an object accelerates?

mass

potential energy

velocity

weight

22.

1 point

The table below shows the time it takes four cars to go from 0 to 60 km/h.

Based on the information given, which of the following quantities can be compared for the four cars?

average acceleration

instantaneous speed

stopping distance

stopping time

23.

1 point

The graph below shows the speed of an object during a 10 s time interval.

In which of the following time intervals is the speed of the object decreasing?

between 0 s and 2 s

between 2 s and 4 s

between 6 s and 8 s

between 8 s and 10 s

24.

1 point

The diagram below shows the forces acting on a rock.

The weight of the rock is 76 N. An upward force of 106 N is exerted on the rock. What is the net force acting on the rock?

30 N upward

76 N downward

106 N upward

182 N downward

25.

1 point

A car has an oil drip. As the car moves, it drips oil at a regular rate, leaving a trail of spots on the road. Which of the following diagrams of the car’s trail of spots shows the car continuously slowing down?

26.

1 point

Which of the following is an example of a vector quantity?

A student walks 2.0 km north.

An object has a mass of 10.5 kg.

A 1.0 kg object moves at 18 m/s.

A ball has an instantaneous speed of 15 m/s.

27.

1 point

A toy cart that has a weight of 10 N moves with a constant velocity of 2 m/s to the right on a horizontal table. According to Newton’s laws of motion, which of the following statements is correct?

The table exerts a force of 10 N upward on the toy cart.

The toy cart exerts a force of 10 N upward on the table.

The toy cart exerts a force of 2 N downward on the table.

The table exerts a force of 2 N to the right on the toy cart.

28.

1 point

The diagram below shows a ball moving in a circular path.

Which of the following would cause the ball to fly off in a straight-line path?

decreasing the mass of the ball

changing the velocity of the ball

increasing the radius of the ball’s path

removing the centripetal force on the ball

29.

1 point

The graph below shows velocity measurements made as a car moved north for 25 s.

How far did the car move during the first 15 s of the trip?

20 m

25 m

300 m

500 m

30.

1 point

A ball has a mass of 0.1 kg and an initial velocity of 20 m/s. The ball is given an acceleration of 30 m/s2 for 5 s.

What is the net force on the ball during acceleration?

0 N

3 N

10 N

15 N

31.

1 point

Which of the following statements best explains why it is usually easier to keep a sliding object moving than it is to start the object moving?

Kinetic friction is typically equal to static friction.

Kinetic friction is typically less than static friction.

Kinetic friction is a force that resists attempts to start an object moving.

Kinetic friction is a force that opposes the sliding of two objects over each other.