Question

If air is blown with a straw under the pans of a physical balance present in equilibrium position, then that pan:
(correct answer + 1, wrong answer - 0.25)

• A. Rises up.
• B. Remains in the same position.
• C. Lowers down.
• D. Rises or lowers depending upon the velocity of air blown.

Answer 1

The correct option is C Lowers down.

As the air is blown, the speed of air particles is more than the surrounding air. So, there would be an air pressure, $\frac{1}{2}\rho v^2$. So, the pan will lower down.