A 0.30 kg stone attached to a 0.8 m long string is rotated in a horizontal plane. The string makes an angle of 15° with the horizontal. Determine the speed of the stone.
the vertical component of the centripetal force must balance the force of gravity.
Radius of circle = 0.8 * cos 15 = 0.773m centripetal force = mv^2/r. This is horizontal component of force in string. Use tan 15 to get vertical component.
Vertical component = mV^2/r * tan 15 = mg; V^2 = gr/tan 15 V= 5.31