Question

The gravitational force causes
(A) Tides
(B) None of them
(C) Motion of moon
(D) Both (a) and (c)

Answer 1

Hint:We know gravitational force is a type of central force. Central forces are those which do not depend upon the path. So, the gravitational force can act upon long distances and does not have to care about the intervening medium between the two bodies. Also, one thing to keep is that gravitational force is always attractive in nature. Also, the universal law of gravitation holds at any place in the universe.

Complete answer:
The moon moves around the earth in a circular orbit. Although the orbit is not circular in actual, it is elliptical. Whenever the body moves in a circular motion, centripetal force acts on it and in case of motion of moon around the earth, the centripetal force is provided by the gravitational force. So, option C holds.Also, the tides and the ocean currents are caused due to the gravitational pull of the moon. The moon exerts tidal force and due to this tidal force the high and low tides are caused. So, option A also, holds.

So, the correct option is D.

Note:The tidal force causes the water to bulge out on the side which is closest to the moon and the side which is farthest from the moon. The gravitational force is directly proportional to the masses of the two bodies and it is inversely proportional to the square of the distance between the two bodies. The gravitational force exerted by earth on all the objects on its surface and in the sky is called gravity.