Question

A loudspeaker converts electrical energy into the kinetic energy of the speaker. This kinetic energy is transferred to air, and the motion of the air is the sound that people hear.

An illustration of speaker with a wide arrow away from it labeled electrical energy 100 J and it splits into 3 arrows labeled sound energy 80 J, thermal energy ? J, and friction 5 J.
How much thermal energy is put out by the speaker?

5 J
15 J
80 J
100 J

Answer 1

100 J in - 80 J sound - 5 J friction = 15 J thermal energy. So the answer is 15 J.