Question

A ball of mass m = 0.2 kg is attached to a (massless) string of length L = 3 m and is undergoing circular motion in the horizontal plane, as shown in the figure.

What should the speed of the mass be for θ to be 46°?


What is the tension in the string?

Answer 1

I guess we are talking about the ball hanging from a hook and 46 degrees above vertical?

Ac = m v^2/r
T = tension
T sin 46 = m v^2/r
T cos 46 = m g
so
tan 46 = v^2/(rg)
v^2 = r g tan 46
but
r = 3 sin 46
so
v^2 = (3 sin 46)(9.8)tan 46

Answer 2

12