Chapter 9 Test

_____ is the ability to make something move.

• Mechanical energy

• Chemical energy

• Motion

• Inertia

Answer explanation

Mechanical energy is the ability to do work by making something move. It encompasses both kinetic and potential energy, making it the correct choice for the ability to cause motion.

A fixed unmoving object or location is ____.

• potential energy

• a joule

• a reference point

• effort force.

Answer explanation

A fixed unmoving object or location is referred to as a reference point. It serves as a basis for comparison in measuring motion or position, distinguishing it from terms like potential energy or effort force.

_____ is the change of an object’s position.

• Kinetic energy

• Motion

• Speed

• Resistance

Answer explanation

Motion is defined as the change of an object's position over time. Kinetic energy refers to the energy of motion, speed measures how fast an object moves, and resistance relates to opposing forces, making 'motion' the correct answer.

The ____ of an object is determined by its mass and velocity.

• inertia

• effort force

• momentum

• stored energy.

Answer explanation

The momentum of an object is defined as the product of its mass and velocity. Therefore, the correct answer is momentum, as it directly relates to both mass and velocity.

_____ occurs whenever an object speeds up, slows down, or changes direction.

• Momentum

• Inertia

• Friction

• Acceleration

Answer explanation

Acceleration occurs when an object speeds up, slows down, or changes direction. It is the rate of change of velocity, making it the correct answer to the question.

The resistance to a change in motion is called ____.

• inertia

• friction

• effort force

• velocity

Answer explanation

The resistance to a change in motion is known as inertia. It describes an object's tendency to remain at rest or in uniform motion unless acted upon by an external force, making it the correct choice.

7. Henry usually runs about 7.5 mi/hr. Write acceleration, distance, speed, or velocity for each example. Answers may be used more than once.

• speed

• acceleration

• distance

• velocity

Answer explanation

Henry's running speed of 7.5 mi/hr refers to how fast he is moving, which is defined as speed. Speed is a scalar quantity that indicates the rate of motion, without considering direction.

On the day of the race, Henry ran along the track toward the east at 7.5 mi/hr. Write acceleration, distance, speed, or velocity for each example. Answers may be used more than once.

• velocity

• acceleration

• distance

• speed

Answer explanation

Henry's movement toward the east at 7.5 mi/hr describes his velocity, which includes both speed and direction. Therefore, the correct answer is velocity.

9. The runner at the front of the race suddenly stumbled over a piece of gravel. His speed slowed. Write acceleration, distance, speed, or velocity for each example. Answers may be used more than once.

• acceleration

• distance

• speed

• velocity

Answer explanation

The runner's speed slowed due to stumbling, indicating a change in speed over time, which is defined as acceleration. Thus, the correct choice is acceleration.

10. Henry increased his speed, passed the runner, and won the race. Write acceleration, distance, speed, or velocity for each example. Answers may be used more than once.

• acceleration

• distance

• speed

• velocity

Answer explanation

Henry's increase in speed indicates a change in velocity over time, which is defined as acceleration. Therefore, the correct choice for this example is acceleration.