(adsbygoogle = window.adsbygoogle || []).push({}); 1. A mass attached to a 50-cm long string starts from rest and is rotated 40 times in 1.00 min before reaching a final angular speed. Determine the angular acceleration of the mass, assuming that it is constant.

W = Delta Theta/Delta Time

Average Acceleration = Delta W/Delta time

W = Wo + at

Theta = Wo(t) + 1/2at^2

W^2 = Wo^2 + 2a(Theta)

3. I started by finding W. It said that the wheel made 40 revolutions in 1 minute so i put:

40 Rev/60 s : 2(pi)/rev

and from this i got: 4.2 Rad/s

Using this i used the formula W = Wo + at:

4.2 = 60a

.07 rev/s^2 = A

the answer in the book says .14 rad/s^2 can anyone point out my mistake?

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Some questions concerning centripetal force.

**Physics Forums | Science Articles, Homework Help, Discussion**