CHAPTER 7 ENERGY AND POWER

What is the definition of work in physics?

• Force applied on an object

• Displacement of an object due to a force

• Product of force and distance moved in the direction of force

• Energy required to move an object

Which of the following is an example of work being done?

• Holding a book in a fixed position

• Pushing a wall without movement

• Lifting a box onto a table

• Sitting on a chair

A boy pushes a 10 kg box with a force of 50 N for 4 m. How much work is done?

• 50 J

• 100 J

• 200 J

• 400 J

Which statement about power is true?

• Power is the rate at which work is done

• Power is measured in joules

• Power is energy stored in an object

• Power is independent of time

A motor does 500 J of work in 5 seconds. What is its power output?

• 50 W

• 100 W

• 250 W

• 500 W

The principle of conservation of energy states that:

• Energy can be created

• Energy is always lost

• Energy cannot be created or destroyed, only transformed

• Energy is always increasing

Which of the following factors affects gravitational potential energy?

• Mass and height

• Speed and height

• Mass and speed

• Force and displacement

What happens to kinetic energy if the velocity of an object doubles?

• It remains the same

• It doubles

• It quadruples

• It reduces to half

A stretched rubber band has what kind of energy?

• Kinetic energy

• Gravitational potential energy

• Elastic potential energy

• Heat energy

A pendulum swings back and forth. At which point is its kinetic energy the highest?

• At the top of the swing

• At the lowest point of the swing

• Halfway to the top

• At any random point