Question

An object moves in uniform circular motion at 25 m/s and takes 1.0 second to go a quarter circle. What is the radius of the circle?
R = _____ m

Answer 1

C=2$\pi$r

100=2$\pi$r

 2$\pi$ you get 6.28
then you divide 100 and 6.28 and get 15.92.
you can round it and get 16. 

Answer 2

Object Motion: 25 m/s

Circumference of Circle: 
1/4 Circumference of Circle in 1 second = 25 meters
25 meters times 4 = Circumference of Circle 
Circumference = 100 meters

Formula to Find Circumference of Circle: (work opposite)
C = 2πr

100 = 2πr          divided
100/2π = r         simplify
50/π = r         (exact radius)

Answer:
50/π meters = r         (exact radius)