# Forces Review

16 Questions  Settings  The following 16 questions cover material on the Forces exam.

Questions and Answers
• 1.
Two people are pushing a large box forward across the floor, one with a force of 50 N and the other with a force of 30 N. If the friction force is 20 N, and the mass of the box is 4 kg, then what is its acceleration?[State only the magnitude of your answer, to the ones place. Omit units.]
• 2.
A 30-kg box, on Earth, is being pushed forward with a force of 75 N. If the coefficient of kinetic friction μk = 0.22, then what is the box's acceleration?[State only the magnitude of your answer, to three decimal places. Omit units.]
• 3.
An astronaut is inside of the International Space Station. Which of the following statements about him are true?
• A.

The Earth's gravity does not extend to the astronaut, therefore he doesn't have a weight.

• B.

The astronaut has a weight that is only slightly less than while standing on the Earth.

• C.

The astronaut is "weightless" in that he is falling.

• D.

The astronaut has an apparent weight that is only slightly less than while standing on the Earth.

• 4.
An object is moving forward at a constant speed. Which of the following statements MUST be true?
• A.

The object is experiencing a net force in the direction of motion.

• B.

There are no forces acting on the object.

• C.

There cannot be only one force on the object.

• D.

The object has a forward acceleration.

• 5.
What force is needed to slow a 2000-kg car from 18 m/s to 6 m/s in 4 seconds?[State only the magnitude of the force, to the ones place. Omit units.]
• 6.
A sled is going 12 m/s when it slides onto an asphalt road and begins to slow down due to friction. If the coefficient of kinetic friction μk = 0.30, how long will it take the sled to stop?[State the time in seconds, without units, to the hundredths place.]
• 7.
An object cannot move unless a force acts upon it.
• A.

True

• B.

False

• 8.
What is the apparent weight of a 60-kg woman in an elevator, if the elevator is accelerating downward at 2 m/s2?[State only the magnitude of your answer, to the ones place. Omit units.]
• 9.
A car strikes an insect while speeding down the highway. True or False: The car applies a greater force to the insect than the insect does to the car.
• A.

True

• B.

False

• 10.
What is the gravitational force between the Moon and an 85-kg astronaut that is standing on it?For the Moon: mass = 7.348E22 kg, radius = 1.737E6 mGravitational constant G = 6.674E-11[State only the magnitude of your answer, to the ones place. Omit units.]
• 11.
Which of the following statements are true pertaining to a 40-kg box sliding down a steep hill?
• A.

The normal force is 392 N.

• B.

The normal force is less than 392 N.

• C.

The normal force is greater than 392 N.

• 12.
True or False: When a person walks, the friction force on the person's feet acts forward.
• A.

True

• B.

False

• 13.
A 50-kg kid on a 5-kg skateboard pushes on a tree with a force of 100 N. What is the kid's acceleration, as he "recoils" backward from the tree?[State only the magnitude of your answer, to the tenths place. Omit units.]
• 14.
Isaac Newton was born in the _________ in rural England.
• A.

1500s

• B.

1600s

• C.

1700s

• D.

1800s

• 15.
True or False: If a car is accelerating to the right, then it is moving to the right.
• A.

True

• B.

False

• 16.
This 94-kg man is hanging motionless from a hook, looped over a wire, as shown. The wire is completely level or horizontal from the hook to the wall. If the wire hits the ceiling at an angle of 15 degrees, then what is the tension in the horizontal section of wire?[State only the magnitude of your answer, to the ones place. Omit units.]