Question

2.1.2 quiz: types of energy
question 4 of 10
which object has the least thermal energy?
a. a 2 kg brick at 20°c
b. a 4 kg brick at 20°c
c. a 2 kg brick at 25°c
d. a 4 kg brick at 25°c

Explanation:

Thermal energy depends on mass and temperature (for the same material, like bricks here). The formula for thermal energy (simplified, since specific heat \(c\) is same for all bricks) is \(Q = mc\Delta T\) (but here we compare relative values). For same temperature, less mass means less thermal energy; for same mass, lower temperature means less.

• Compare A and B: Same temp (\(20^\circ C\)), A has less mass (2 kg vs 4 kg) → A < B.
• Compare A and C: Same mass (2 kg), A has lower temp (\(20^\circ C\) vs \(25^\circ C\)) → A < C.
• Compare A and D: A has less mass (2 vs 4) and lower temp (20 vs 25) → A has least.

Answer:

A. A 2 kg brick at \(20^\circ\)C