Chapter 12, Problem 25A

Why is a stick with a wad of clay at the top easier to balance on the palm of your hand than an empty stick?

To determine

To explain: A reason for the easier balancing on the palm than an empty stick.

Answer to Problem 25A

The stick at the top of wad of the clay has lesser angular velocity. Thus, larger rotational inertia helps it to stay stable.

Explanation of Solution

Introduction:

More the angular velocity of the stick on the palm, more chances are it to drop or unbalance.

Angular momentum $L$ is always conserved.

  $L=I\omega$

Where $I$ is Rotational Inertia and $\omega$ is angular velocity.

If rotational inertia is more, lesser will be its angular velocity. With the lesser angular velocity, it is easier to balance a stick on the top of a wad of clay on the palm. But, in the case of balancing an empty stick, Rotational Inertia is lesser, which gives momentum. It starts spinning and swirling and with the decrease in its angular velocity, stick unbalances.

Conclusion:

Thus, the stick with the wad of clayat the top has more rotationalinertia compared to an empty stick.