Question

9. State which of the following situations are possible and give an example for each of these: (a) an object with a constant acceleration but with zero velocity (b) an object moving with an acceleration but with uniform speed. (c) an object moving in a certain direction with an acceleration in the perpendicular direction. ​

Answer 1

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(a) an object with a constant acceleration but with zero velocity

• Let say a stone is thrown in vertical direction with initial speed u. As the time passes its velocity decreases and at the maximum height it attained, its velocity is zero but it has an acceleration (9.8)m/s² in the downward direction due to gravity.

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(b) an object moving with an acceleration but with uniform speed.

• Because, the velocity keeps on changing due to continuous change in the direction of motion. Therefore, circular motion is an example of an object moving with an acceleration but with uniform speed.

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(c) an object moving in a certain direction with an acceleration in the perpendicular direction.

• When a pebble is tied with an end of string and it is whirled in horizontal circular motion with the other end of the string at the centre of circular path, then it has a constant magnitude of centripetal acceleration towards the centre. Hence the acceleration is in perpendicular direction to the motion of pebble.

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Answer 2

Explanation:

(a) an object with a constant acceleration but with zero velocity

=> Let say a stone is thrown in vertical direction with initial speed u. As the time passes its velocity decreases and at the maximum height it attained, its velocity is zero but it has an acceleration (9.8)m/s² in the downward direction due to gravity.

(b) an object moving in a certain direction with an acceleration in the perpendicular direction.

=> When a pebble is tied with an end of string and it is whirled in horizontal circular motion with the other end of the string at the centre of circular path, then it has a constant magnitude of centripetal acceleration towards the centre. Hence the acceleration is in perpendicular direction to the motion of pebble.