Question

10. A stone of mass 'm' is rotated in a circular path with a
uniform speed by tying a strong string with the help of
your hand. Answer the following questions:
(1) Is the stone moving with a uniform or variable
speed ?
(ii) Is the stone moving with a uniform acceleration?
In which direction does the acceleration act?
(iii) What kind of force acts on the hand and state its
direction ?​

Answer 1

1) The stone is moving with a uniform speed.

In a particular time 't' the stone covers a distance of 2πr, r being the length of string. Thus, speed = 2πr/t = constant.

2) The stone is moving with a non uniform acceleration.

The velocity changes as the direction of stone changes at every point of the circumference of circular path in which it's rotating. Since the velocity changes, acceleration changes. The direction of acceleration is tangential to the point on circumference.

3) On the hand, centrifugal force acts. The centrifugal force acts away from the centre, that is away from the hand.

[The centrifugal force acts on the source of motion and the centripetal force acts on the body which is in circular motion.]

Answer 2

AnSwEr:–

(i) The stone is moving with a uniform speed.

(ii) The stone is moving with a uniform acceleration because as it's speed is uniform but it is also changing it's direction constantly. It's direction is along the tangent to a point on the circle.

(iii) Centrifugal force is acting on the hand and it's direction is opposite to the direction of centripetal force which means away from the centre.

$\rule{200}2$