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## Homework Statement

Can someone check if this is right? The time seems okay, but the work I feel is wrong

A ball with moment of inertia 0.1kg · m2 is rotating on a table, but

friction is slowing it down with constant angular acceleration. The ball is originally spinning at 2π radians per second, but slows down to 10 percent of that value in 2 seconds

1) How long does it take the ball to come to rest (time since it began spinning)

2)How much work is done on the ball to bring it to rest

## Homework Equations

1)Since angular acceleration is constant, we use ∆ω = α∆t

2)W = ∆K = Kf − Ki = 0 −1/2Iω

## The Attempt at a Solution

1) Since I have the ball spinning at 2π/sec, and it slows down -10% of the original speed in two seconds, so i plug in the information into the equation. so Δw= (-.10)(2π)/2sec which equals -.314159. Which then I can solve for t. New equation: t=Δw/α. So -.314159/-.628318= 5 Sec.

2) (-1/2)(.1kg*m^2)(.628318)^2=-.0197J