- #1
Vanessa23
- 41
- 0
[SOLVED] Grindstone angular acceleration
Object: a disk-shaped grindstone of mass 1.69 kg and radius 7.95 cm that operates at 707 rev/min. When the power is shut off, you time the grindstone and find it takes 32.1 s for it to stop rotating. What is the angular acceleration of the grindstone? (Assume constant angular acceleration.)
W=.5mv^2
V=distance/t
W=Wo+at
a=alpha, which is angular acceleration
V=[707*(2pi/60)]/32.1 = 2.31m/s
W=0
Wo=.5(1.69)(4.50^2) = 4.50J
0=4.50+a(32.1)
therefore, a=-.140 rad/s^2
however, this is the wrong answer according to the program. It didn't have a problem with the units though, so I don't know what I am doing wrong. Please point out any wrong assumptions or completely wrong or silly mistakes. THANK YOU!
Homework Statement
Object: a disk-shaped grindstone of mass 1.69 kg and radius 7.95 cm that operates at 707 rev/min. When the power is shut off, you time the grindstone and find it takes 32.1 s for it to stop rotating. What is the angular acceleration of the grindstone? (Assume constant angular acceleration.)
Homework Equations
W=.5mv^2
V=distance/t
W=Wo+at
a=alpha, which is angular acceleration
The Attempt at a Solution
V=[707*(2pi/60)]/32.1 = 2.31m/s
W=0
Wo=.5(1.69)(4.50^2) = 4.50J
0=4.50+a(32.1)
therefore, a=-.140 rad/s^2
however, this is the wrong answer according to the program. It didn't have a problem with the units though, so I don't know what I am doing wrong. Please point out any wrong assumptions or completely wrong or silly mistakes. THANK YOU!