Chapter 2, Problem 20RQ

If you’re in a smooth-riding bus that is going at $50\text{km}/\text{h}$ and and you flip a coin vertically, what is the horizontal velocity of the coin in midair?

To determine

The horizontal velocity of the coin in midair when it is flipped vertically in a smooth riding going at $50\text{km}/\text{h}$.

Answer to Problem 20RQ

The horizontal velocity of the coin in midair when it is flipped vertically in a smooth riding going at $50\text{km}/\text{h}$ is $50\text{km}/\text{h}$.

Explanation of Solution

The ability of a body, the resist the variation in the existing state is known as inertia. It means that a body will continue to be in a state of motion, at the same speed until an external force acts upon it. If a person tosses a coin in a smooth moving bus going with velocity $50\text{km}/\text{h}$. Then, the horizontal velocity of the coin in mid-air will be the same as the velocity of the bus, that is $50\text{km}/\text{h}$. It is because of the force of inertia, which is acting over the coin while pushing it in the direction of moving the bus. This means that the velocity of object inside the bus will have same speed as that of bus, with respect to ground.

Conclusion:

Therefore, the horizontal velocity of the coin in mid-air is $50\text{km}/\text{h}$.