In figure, a block of weight 15 N is hanging from a rigid support by a string. What force is exerted by —

(a) block on the string,

(b) string on the block.

Name them and show them in the diagram.

The gravitational force between two bodies is —

1. always repulsive
2. always attractive
3. attractive only at large distances
4. repulsive only at large distances.

The law of gravitation was given by :

1. Thomas Alva Edison
2. Alexander Graham Bell
3. Sir Isaac Newton
4. Albert Einstein

The forces of attraction acting between two bodies is :

1. directly proportional to the product of their masses
2. directly proportional to the square of the distance between them
3. inversely proportional to the square of the distance between them
4. both (a) and (c)