PART - 1 CH - 1 Units and Measurements — Physics STD 11 Science — Question

What causes the rolling sound of thunder?

Give two uses of polar satellites.

The electrochemical equivalent of a material depends on:

1. The nature of the material.
2. The current through the electrolyte containing the material.
3. The amount of charge passed through the electrolyte.
4. The amount of this material present in the electrolyte.

Why bells are made of metal and not wood?

When a body is weighed on an ordinary balance we demand that the arm should be horizontal if the weights on the two pans are equal. Suppose equal weights are put on the two pans, the arm is kept at an angle with the horizontal and released. Is the torque of the two weights about the middle point (point of support) zero? Is the total torque zero? If so, why does the arm rotate and finally become horizontal?

Name the type of motion associated with the molecules of a gas.

A stone, when thrown on a glass window, smashes the window pane to pieces. But a bullet fired from a gun passes through making a hole. Why?

Write dimensional formula for compressibility.

One of your friends argues that he has read in the previous chapters that there can be no electric field inside a conductor. And hence there can be no current through it. What is the fallacy of this argument?

Explain this statement clearly:
“To call a dimensional quantity ‘large’ or ‘small’ is meaningless without specifying a standard for comparison”. In view of this, reframe the following statements wherever necessary:

1. Atoms are very small objects
2. A jet plane moves with great speed
3. The mass of Jupiter is very large
4. The air inside this room contains a large number of molecules
5. A proton is much more massive than an electron
6. The speed of sound is much smaller than the speed of light.