# A child is twirling a 0.0120-kg plastic ball on a string in a horizontal circle whose…

A child is twirling a 0.0120-kg plastic ball on a string in a

horizontal circle whose radius is 0.100 m. The ball travels once

around the circle in 0.500 s. (a) Determine the centripetal force

acting on the ball. (b) If the speed is doubled, does the

centripetal force double? If not, by what factor does the

centripetal force increase?

Question I need answered is, Why is gravity not considered when

solving this problem?