physics question #2968

Francis, a 40 year old male from Ottawa asks on October 6, 2005,


When a ball is rotated at the end of a string in a horizontal circle (parallel to the ground) what balances the force of gravity to prevent the ball from falling straight down? I understand that inertia balances the tension of the string (the centripetal force) in the horizontal plane, but I am unsure of how to describe what is doing the balancing of gravity in the vertical plane.

viewed 13165 times

the answer

Jess Brewer answered on October 7, 2005, A:

The circular path of the ball may be horizontal, but the string isn't. It drops a bit from the pivot point to the ball, and so the "centripetal" force is actually part horizontal and part vertical. The vertical part balances the downward force of gravity.

Add to or comment on this answer using the form below.
(required if you would like a response)
Note: All submissions are moderated prior to posting.
If you found this answer useful, please consider
making a small donation to