the string provides the centripetal force to keep the ball moving in a circle
the tension is less at the top (with gravity assisting)
... and more at the bottom (having to overcome gravity)
the difference (64.0 N) is twice the weight
2 m g = 64.0 N
You swing a 1.40m long string with a metal ball attached to its end in a vertical circle, such that the speed of the ball does not change but the rope is always taut. The tension in the string when the ball is at the bottom of the circle is 64.0N more than the tension when the ball is at the top. Find the mass of the ball.
2 answers
well first tension at bottom
Tb = mg + m v^2/R
then at top
Tt = m v^2/R - mg
Tb-Tt = 2 m g = 64
so
m = 32/g
Tb = mg + m v^2/R
then at top
Tt = m v^2/R - mg
Tb-Tt = 2 m g = 64
so
m = 32/g
2 answers