Posted by **Robert** on Sunday, December 7, 2008 at 9:46pm.

(#1.) A top starting from 40 rad/s takes 200 rad to stop. What is its rotational acceleration? (a constant)

(#2.) A stationary 100 Kg circular object (r= 0.20 m) is on a 35 degree incline. The coefficient of rolling friction between the block and the incline is 0.01. If it moves for 5 seconds, what is the angular displacement of the object at this time? (disregard torque)

For #1, I did: wf^2 = wi^2 + 2a(change in radians) and got a=4 radians/second^2. Is this right?

(I don't know how to do #2)

- Physics - Rotational Motion -
**bobpursley**, Sunday, December 7, 2008 at 9:55pm
Yes on 1.

On 2, I don't know what a circular object is (sphere, cylinder, hoop). Each of those has a differing moment of inertial, and absorbs rolling friction differently.

- Physics - Rotational Motion -
**Robert**, Sunday, December 7, 2008 at 9:57pm
The 2d drawing that goes with #2 shows a circle at the top of an incline. \

- Physics - Rotational Motion -
**bobpursley**, Sunday, December 7, 2008 at 9:59pm
a circle could be a hoop,or a thin wheel.

- Physics - Rotational Motion -
**Robert**, Sunday, December 7, 2008 at 10:03pm
Whichever one is the easiest to analyze.

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