Laws of Motion — Physics STD 11 Science — Question

A ball is thrown in the air. Is the ball is momentum conserved when it is in air? If not, then why not?

State the law of conservation of momentum.

What is meant by internal energy?

The free surface of a liquid resting in an inertial frame is horizontal. Does the normal to the free surface pass through the centre of the earth? Think separately if the? The free surface of a liquid resting in an inertial frame is horizontal. Does the normal to the free surface pass through the centre of the earth? Think separately if the liquid is.

1. At the equator.
2. At a pole.
3. Somewhere else.

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?

If a particle is moving on a straight line passing through the origin, then what will be its angular momentum relative to the origin?

State with reasons, whether the following algebraic operations with scalar and vector physical quantities are meaningful:

1. adding any two scalars.
2. adding a scalar to a vector of the same dimensions.
3. multiplying any vector by any scalar.
4. multiplying any two scalars.
5. adding any two vectors.
6. adding a component of a vector to the same vector.

What is the weight felt by a person in a lift when it has free fall?

Write three pairs of physical quantities, which have same dimensional formula.

If the value of each of the units of force and length is doubled, then how many times will the value of the unit of energy become?