# Rotational kinematics

1. May 28, 2016

### David112234

1. The problem statement, all variables and given/known data
A wheel of diameter 45.0 cm starts from rest and rotates with a constant angular acceleration of 2.50 rad/s2 . At the instant the wheel has completed its second revolution, compute the radial acceleration of a point on the rim in two ways.

1 Using the relationship aredial2r.

2 From the relationship aredial=v2/r.

2. Relevant equations
v=ωr
rotational kinematics
aredial2r
aredial=v2/r.

3. The attempt at a solution

α= 2.5
it says second rotation so θ= 2π*2 = 12.57

θ = ωt + ½ α t2
12.57 = ½ 2.5 t2
t= 3.171

ω = ω + α t
ω = 2.5 (3.171)
ω = 7.927

aredial2r
a = 7.9272 * 22.5 = 1413.716694

2 should be the same answer since the equations are equal

2. May 28, 2016

### PeroK

Is the diameter of the wheel $45m$ or $45cm$?

3. May 28, 2016

### David112234

got it, there was my mistake, thank you