Question

State the energy changes that occur when:

(i) a car moves up a slope

(ii) a solar-powered calculator is in use.

(iii) a clock spring is winded.

(iv) a battery lights up a bulb.

(v) a moving truck is brought to rest by applying the brakes.

Answer 1

(i)

1. A car moving up the hill – We know that a body to move upward initially requires energy to move which is converted and stored as the potential energy of the car.
2. This initial energy by virtue of its upward motion is kinetic energy.
3. The car moving uphill converts from kinetic energy and potential energy.

(ii)

The energy transformation in a solar calculator is from radiant (light) energy to electrical energy.

(iii)

During the winding of the spring of a clock, the kinetic energy gets converted into the stored potential energy of the spring.

(iv)

1. When a battery lights a bulb, the first energy transformation takes place in the battery and then in the bulb.
2. In the battery, the chemical energy gets converted into electrical energy.
3. In the bulb, the electrical energy from the bulb gets converted into heat energy and then into light energy.

(v)

A mechanical brake applies a friction force to convert the kinetic energy of the vehicle into thermal energy which then dissipates into the atmosphere.