Circular Motion Problem Solutions

1. What would happen to the centripetal force required to keep an object going in a circle if the radius of a circle was doubled?

2. How many times the centripetal force would you have if a car slowed from 60 mph to 20 mph going around a curve?

 

60 -> 20 mph = 20/60 = 1/3 the speed

 

3. Kent spins in his chair with a frequency of 0.5 Hz. What is the period of his spin?

 

F = 0.5 Hz

T = 1/f =1/0.5 = 2 s

 

4. A record takes 1.3 s to make one complete rotation. An object on this record is 0.12 m from the center.  What is its velocity?

 

T = 1.3 s

r = 0.12 m

V = ?

 

 

5a. The pilot of a 60,500 kg jet plane is flying in circles whose radius is 5.00 x 10⁴ m.  It takes 1.8 x 10³ s to make one rotation.  What is the velocity of the plane?

 

m = 60,500 kg

r =  5.00 x 10⁴ m

T = 1.8 x 10³ s

 

5b. The pilot of a 60,500 kg jet plane is flying in circles whose radius is 5.00 x 10⁴ m.  It takes 1.8 x 10³ s to make one rotation.  How much centripetal force would there be?

 

m = 60,500 kg

r =  5.00 x 10⁴ m

T = 1.8 x 10³ s

v =175 m/s

 

6. What is the centripetal acceleration of a bike traveling a tangential speed of 8 meters per second in a circle that has a radius of 5 meters?

 

a_C = ?

v = 8 m/s

r = 5 m