Gravitation Science - Gravitation

Two particles are placed at some distance from each other. If, keeping the distance between them unchanged, the mass of each of the two particles is doubled, the value of gravitational force between them will become:

A metal in which even iron can float is:

1. Sodium.
2. Magnesium.
3. Mercury.
4. Manganese.

Two objects of different masses falling freely near the surface of moon would:

1. Have same velocities at any instant.
2. Have different accelerations.
3. Experience forces of same magnitude.
4. Undergo a change in their inertia.

An object weighs 10N in air. When immersed fully in a liquid, it weighs only 8N. The weight of liquid displaced by the object will be:

1. 2N
2. 8N
3. 10N
4. 12N

The following statements are true or false:
The force of gravitation between two objects depends on the nature of medium between them.

The following statements are true or false:
The acceleration due to gravity acting on a freely falling body is directly proportional to the mass of the body.

State whether the following statements are true or false:
'Archimedes’ principle can also be applied to gases.

State whether the following statements are true or false:
The buoyant force depends on the nature of object immersed in the liquid.

The following statements are true or false:
A falling stone also attracts the earth.

Fill in the following blanks with suitable word:
In order to sink in a fluid, the density of an object must be _____ than the ______ of the fluid.

Fill in the following blanks with suitable word:
It is the _______ force which makes objects appear lighter in water.

Fill in the following blanks with suitable word:
Force acting on a unit area is called _______.

Fill in the following blanks with suitable word:
Snow shoes work by spreading out a person’s _______ over a much bigger ______.

Fill in the following blanks with suitable word:
A heavy ship floats in water because its ______ density is less than that of water.

What is the value of relative density of water?

Why does a block of wood held under water rise to the surface when released?

A mug full of water appears light as long as it is under water in the bucket than when it is outside water. Why?

What happens to the gravitational force between two objects when the distance between them is (i) doubled (ii) halved?

If a fresh egg is put into a beaker filled with water, it sinks. On dissolving a lot of salt in the water, the egg begins to rise and then floats. Why?

A stone and the earth attract each other with an equal and opposite force. Why then we see only the stone falling towards the earth but not the earth rising towards the stone?

What happens to the buoyant force as more and more volume of a solid object is immersed in a liquid? When does the buoyant force become maximum?

What is the difference between the density and relative density of a substance?

Explain why, when a person stands on a cushion, the depression is much more than when he lies down on it.

When is the pressure on the ground more-when a man is walking or when a man is standing? Explain.

If the relative density of a substance is 7.1, what will be its density in SI units?

Universal law of gravitation states that every object exerts a gravitational force of attraction on every other object. If this is true, why don’t we notice such forces? Why don’t the two objects in a room move towards each other due to this force?

Suppose a planet exists whose mass and radius both are half those of the earth. Calculate the acceleration due to gravity on the surface of this planet.