Question

A bob of mass m attached to the end of a string is swung in a horizontal circle,as shown. If the string were suddenly cut when the bob is at point A , the subsequent motion of the bob would be :

• A. to move to the right
• B. to move to the left
• C. to move to the top of the page.
• D. to move to the bottom of the page.
• E. to move up and to the left.

Answer 1

Answer: (C)

to move to the top of the page.

The velocity of the bob at the moment just before cutting the string is along the tangent of the circle at the point, that is, upwards.

Just after the string is cut, centripetal force stops acting on the bob, and the bob continues to move with the same velocity.

Hence the bob, after the string is cut, its subsequent motion is to move towards the top of the page.