Question

two friends bought phones that cost different amounts but had identical batteries. after using the phones for a while, both friends had to turn them off to let the batteries cool. this table shows how the temperature of each battery changed over 5 minutes.

battery	initial temperature (°c)	final temperature (°c)
battery in the more expensive phone	37	25

during this time, thermal energy was transferred from each battery to the surroundings.
options:

• the surroundings... each battery
• each battery... the surroundings

Explanation:

To determine the direction of thermal energy transfer, we analyze the temperature change of the batteries. The initial temperature of both batteries is \( 37^\circ\text{C} \), and the final temperatures are \( 22^\circ\text{C} \) (less expensive) and \( 25^\circ\text{C} \) (more expensive), both lower than the initial. Thermal energy flows from a higher - temperature object to a lower - temperature object. Since the batteries are at a higher temperature than the surroundings (as they are cooling down), thermal energy is transferred from each battery to the surroundings.

Answer:

each battery... the surroundings