Chapter 9, Problem 46A

Consider the kinetic energy of a fly in the cabin of a fast-moving train. Does it have the same or different kinetic energies relative to the train? Relative to the ground outside?

To determine

To identify:Whether the fly have the same or different kinetic energies relative to the train and relative to the ground outside.

Answer to Problem 46A

The fly has different kinetic energy relative to the train and to the ground outside.

Explanation of Solution

Introduction:

The kinetic energy of the object is,

  $KE=\frac{1}{2}m{v}^2$

Here, $m$ is the mass and $v$ is the speed.

The kinetic energy of a fly in the cabin of a fast moving train is considered. The kinetic energy of an object will depends on its mass and speed.

The speed of the fly in the cabin relative to the train will be different. If an object move, then it means that it is capable to do work. The fly in the cabin has a kinetic energy as well as energy of motion.

The speed of the fly in the cabin is different, relative to the ground outside. Because, the fly in the cabin will move faster relative to the ground.Hence, the fly has different kinetic energy relative to the train and to the ground outside.

Conclusion:

Thus, the fly has different kinetic energy relative to the train and to the ground outside.