Centripetal Force?

Question

A 1.5 kg mass is whirled in a horizontal circle at the end of a .8 meter long cord. If the cord stands out at an angle of 40 degrees from the vertical, calculate

(1) the radius of the circle produced by the path of the mass
(2) the angular speed of the mass in radians/second
(3) the centripetal force acting on the mass.

Answer 1

The centripital force is provided by the horizontal component of the tension in the string

Fc = T sin 40 degrees

This is the answer to part (3).

The radius of the circular motion is

r = ( .8 m ) sin 40 degrees

and centripetal acceleration can be written as

r w^2

where w is the angular velocity.

So put it all together

Fc = m r w^2

You know everything except the angular velocity so solve for w.