Question

What is an example of the first law of thermodynamics? 5.0-g bullet traveling at a

speed of 300 m/s enters a tree and exits the other side with a speed of 150 m/s.

Where did the bullet’s lost kinetic energy go, and how much energy was

transferred?

Answer 1

An example is an air balloon that expands under the sunlight.

The energy of the bullet went to destroy the tree:

$$\Delta E=\frac12m(v_f^2-v_i^2)=-170\text{ J}.$$

The bullet lost 170 J.