Question

The first law of thermal dynamics expresses the relationship between energy, heat and work. The internal energy of a system depends upon the heat absorbed or released by the system and the work done by or done to the system. Delta E=q+w

For example, a ping pong player expends 35 kj/min during play.Which of the following represents Energy and which represents work?

A. The paddle hits the ball

B. muscle contraction

C. ATP in muscles

I'm not sure if i'm thinking about this correctly... I think the player is the system and his surrounding are, obviously, the surroundings. w= work done by the system which would mean A. is in this category. q= Heat absorbed by the system, which would be B and C. Is this right or is it backwards??

Answer 1

Hello!!!
You are thinking on the correct lines. The muscles of the player is the system.

Let me first tell you about ATP. ATP stands for Adenosine Triphosphate which gives energy to the body cells by breaking from ATP to ADP (Adenosine Diphosphate). Thus the ATP supplies energy to the muscles. Hence ATP in muscles is the energy. Now this energy helps the muscles to contract with which the player can hit the ping pong ball with his paddle. So the muscle contraction is the work done by the muscles and the hitting of the paddle is the work done by the paddle on the ball.

Hence, coming back to your initial question,
Option C represents energy.
Option A and B represents Work done.