Chapter 8, Problem 8.1QQ

By what transfer mechanisms does energy enter and leave (a) your television set? (b) Your gasoline-powered lawn mower? (c) Your hand-cranked pencil sharpener?

To determine

The energy transfer mechanism by which energy enter and leave the television set.

Answer to Problem 8.1QQ

The energy enters in the form of electrical energy, electromagnetic radiation and energy leaves in the form of heat, mechanical waves and electromagnetic radiation.

Explanation of Solution

In the television set, the energy enters in the form of electrical energy for the power and in the form of the electromagnetic radiation for the signal purpose.

The energy leaves by the television in different forms. First type of the energy is left in the form of the heat from the hot surfaces of the television into the air, second type of the energy is left in the form of mechanical waves as sound from the speaker and third type of energy form is left in the form of electromagnetic radiation from the television screen.

Conclusion:

Therefore, the energy enters in the form of electrical energy, electromagnetic radiation and energy leaves in the form of heat, mechanical waves and electromagnetic radiation.

To determine

The energy transfer mechanism by which energy enter and leave the gasoline-powered lawn mower.

Answer to Problem 8.1QQ

The energy enters in the form of fuel energy and energy leaves in the form of heat, mechanical waves and work.

Explanation of Solution

In the gasoline-powered lawn mower, the energy enters in the form of fuel energy by using gasoline for the power.

There are three main ways in which the energy leaves the gasoline-powered lawn mower. The energy leaves in the form of the heat from the hot surfaces into air, in the form of mechanical waves as sound and in the form of work on the blades of the grass cutter.

Conclusion:

Therefore, the energy enters in the form of fuel energy and energy leaves in the form of heat, mechanical waves and work.

To determine

The energy transfer mechanism by which energy enter and leave the hand-cranked pencil sharpener.

Answer to Problem 8.1QQ

The energy enters in the form of work in turning the crank and energy leaves in the form of work done on the pencil and mechanical waves as sound.

Explanation of Solution

In the hand-cranked pencil sharpener, the energy enters in the form of the form of work in turning the crank by hand.

There are two main ways in which the energy leaves the hand-cranked pencil sharpener. The energy leaves in the form of mechanical waves as sound from and in the form of work done on the pencil.

Conclusion:

Therefore, the energy enters in the form of work in turning the crank and energy leaves in the form of work done on the pencil and mechanical waves as sound.