Midterm Exam Practice Test 2

A cue ball rolls toward a billiard ball with a velocity of 1.0 m/s east. Both balls have identical masses. What happens to the total momentum after the two balls collide?

• It is greater than the original momentum of the cue ball.

• It is equal to the momentum before the collision.

• It is less than the original momentum of the cueball.

• It is equal to zero.

Why do astronauts in orbiting spacecraft appear weightless?

• Nothing in space exerts a force of gravity on the astronauts.

• The astronauts are in free fall along with the spaceship.

• The astronauts have no mass in space.

• The spaceship exerts equal force on an astronaut from all sides.

Which of the following is NOT an action/reaction force pair?

• the forces between a bat and ball

• the attractive force between a falling ball and Earth

• the force of propulsion and the force of gravity on an airplane

• the forces between a grasshopper and the ground

An ice skater with a mass of 65 kg moves along the ice with a constant velocity of 2.0 m/s. What is the skater's momentum?

• 130 kg·m/s

• 32 kg·m/s

• 130 N

• 32 N

Why does a ball thrown horizontally follow a path that is curved downward?

• There is no acceleration on the ball.

• The ball is accelerated in the horizontal direction only.

• The ball is accelerated by gravity in the vertical direction only.

• The ball is accelerated in both the vertical and horizontal directions.

What must you know to find the momentum of an object?

• mass and acceleration

• acceleration and force

• mass and velocity

• velocity and time

Why does a ball thrown level to the ground move downward?

• There is no force on the ball.

• A force pulls ball in the direction it is thrown.

• Gravity pulls ball toward the ground.

• Forces pull on the ball in both directions.

Air resistance causes the speed of a falling object to

• increase.

• remain unchanged.

• decrease.

• become zero.

A falling object’s terminal velocity is reached when the force of gravity

• is greater than the force of air resistance.

• is less than the force of air resistance.

• is equal to the force of air resistance.

• is the only force acting on the object.

A sled sliding on a flat, icy surface with a constant velocity is best described by

• Newton’s first law of motion for objects at rest.

• Newton’s first law of motion for objects in motion.

• Newton’s second law of motion.

• Newton’s third law of motion.