Two part tension and speed question.

Question

A 240 g block on a 60 cm-long string swings in a circle on a horizontal, frictionless table at 75 rpm.

What is the speed of the block in m/s?

Express your answer using two significant figures.

What is the tension in the string in Newtons?

Express your answer using two significant figures.

Answer 1

r=.6m

Circumference = 2pir=(2)3.14(.6m)= 3.77 m

75 rotations/minute (3.77 m/1 rotation)(1minute/60 seconds)

75*3.77*(1/60) =4.7 m/s

The tension is equal to the centripetal force.

Centripital Force Fc= (m)(v^/r)

m = mass (kg)

v = velocity

r = radius

Fc= (0.24kg) (4.7m/s)^2 /(.6m) = 8.8 Newtons