Question

Which of the following is an example of the first law of thermodynamics?

(A) The specific heat of an object explains how easily it changes temperatures.

(B)While melting, an ice cube remains at the same temperature.

(C) When a refrigerator is unplugged, everything inside of it returns to room temperature after some time.

(D) After falling down the hill, a ball's kinetic energy plus heat energy equals the initial potential energy.

Answer 1

(B) While melting, an ice cube remains at the same temperature. [Here, ∆u = 0, W = Q]
(C) When a refrigerator is unplugged, everything inside of it returns to room temperature after some time.
(D) After falling down the hill, a ball’s kinetic energy plus heat energy equals the initial potential energy.