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## Homework Statement

Here is a diagram:

http://i55.tinypic.com/k18g14.jpg

A ball of mass 0.75 kg on the end of a cord is swung in a circle of radius 1.5 m with a period of 1.5 s as shown in the diagram.

a.) What is the speed of the ball?

b.) What is the acceleration of the ball?

c.) What centripetal force must be exerted by the cord to keep the ball in orbit?

d.) What is the mass of the central object? (Hint: Use Pythagoras' theorem to calculate the force of tension in the string.)

e.) What angle does the cord make with the vertical?

f.) How long is the cord, L?

## Homework Equations

Velocity = 2(pie)r / T (T = period in seconds)

Acceleration centripetal = v^2 / r

Force centripetal = mv^2 / r

## The Attempt at a Solution

I know all parts except for d, e and f

a.) velocity of ball is 6.28 m/s

b.) centripetal acceleration of ball is 26.3 m/s^2

c.) centripetal force of ball is 19.7 N

d.) ??

e.) ?

f.) ?

Thanks