Unit 1: Forces and Motion Test

Why do the action and reaction forces in Newton's third law of motion not balance each other?

• A. The forces act in the same direction.
• B. The forces have different strengths.
• C. The forces act on different objects.
• D. The forces do balance each other because they are equal and opposite.

The photo shows evidence of meteors colliding with the moon. According to Newton’s laws, what can be said about these collisions?

• A. During each collision, the moon exerted a greater force on each meteor than each meteor exerted on the moon.
• B. The moon and meteors exerted equal but opposite forces on each other.
• C. The collisions were so small that no forces acted on either the moon or the meteors during the collisions.
• D. Because the moon has no atmosphere, Newton’s laws cannot be applied to the collisions between the moon and meteors.

The unbalanced force on each object in the collision will cause each object to accelerate.

• First law of motion
• Second law of motion
• Third law of motion

How much additional force would the craft have to exert to achieve the same acceleration if another 52 kg person got onboard the craft?

• A. no additional force is necessary
• B. 8 newtons
• C. 96 newtons
• D. 312 newtons

What kind of object could be represented by line C?

• A. a bird landing in sand
• B. a car accelerating away
• C. a car coming to a sudden stop
• D. a horse slowing from trot to a walk

What change could cause an apple hanging from a tree branch to fall? Choose the correct answer.

• loss of gravity
• loss of a sideways force on the left
• loss of a sideways force on the right
• loss of the upwards force opposing gravity

Objects labeled A, B, and C all have the same distance from each other. The gravitational attraction between objects A and B is less than the attraction between objects B and C. The attraction between objects A and C is less than the attraction between the other two sets of objects. What is the relationship between the masses of objects A, B, and C? Choose the correct answer.

• The mass of object A equals the mass of object C.
• The mass of object A equals the mass of object B.
• The mass of A is less than C, which is less than B.
• The mass of C is greater than B, which is greater than A.

A metal ball sits motionless on a flat surface. Which of these would make the ball move? Choose the correct answer.

• The force of gravity becomes less.
• The force of gravity becomes greater.
• Two equal horizontal opposing forces act upon the ball.
• Two unequal horizontal opposing forces act upon the ball.

Which of these units is the standard international unit of force? Choose the correct answer.

• gram
• pound
• newton
• kilogram

What is gravity? Choose the correct answer.

• a contact force
• a frictional force
• a magnetic force
• a noncontact force