PRACTICE Conservation of Energy

What is mechanical energy composed of?

• The sum of thermal energy and chemical energy in a system

• The sum of potential energy and the kinetic energy in a system

• The sum of nuclear energy and electrical energy in a system

• The sum of sound energy and light energy in a system

How is mechanical energy measured?

• Watts (W)

• Newtons (N)

• Joules (J)

• Pascals (Pa)

Which example illustrates mechanical energy?

• A battery providing electrical energy

• A pendulum having kinetic energy and gravitational potential energy

• A hot cup of coffee emitting thermal energy

• A light bulb emitting light energy

What is the SI unit of work equivalent to?

• 1 Watt (W) times 1 second (s)

• 1 Newton (N) times 1 meter (m)

• 1 Pascal (Pa) times 1 cubic meter (m³)

• 1 Joule (J) times 1 second (s)

When you throw a ball into the air, at what point does the ball have the most kinetic energy?

• When it is at its highest point

• Just after it leaves your hand

• As it starts falling back down

• When it is halfway up

What happens to the potential energy of a ball as it moves down after being thrown into the air?

• It increases

• It remains constant

• It decreases

• It transforms into chemical energy

How is energy transferred when a ball that has been thrown up starts to come back down?

• Potential energy is transferred into kinetic energy

• Kinetic energy is transferred into potential energy

• Kinetic energy is transferred into chemical energy

• Potential energy is transferred into thermal energy

What does the law of conservation of energy state?

• Energy can be created but not destroyed

• Energy is neither created nor destroyed, but it can be lost

• Energy is always transferring, and it is neither created nor destroyed

• Energy can be destroyed but not created

Which of the following is a sign that an energy transfer has occurred?

• A change in color of an object

• A change in motion between objects

• A change in temperature of the surroundings

• A change in the shape of an object

What is another indicator of energy transfer besides a change in motion?

• A change in the electrical charge of a system

• A change in the sound of a system

• A change in the mass of objects

• A change in the brightness of the environment