Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A grinding wheel turns at rpm. When the motor is switched off, it makes more turns before it stops, slowing steadily.
For rotation with steady angular acceleration: , , , with angles in radians (). A point at radius has , tangential acceleration and centripetal acceleration .
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. , , .
Plan. The rotation equations, in radians.
Step 1. (a) , so .
Step 2. (b) .
Answer: (a) . (b) .
Check. The average speed is half of , and . It agrees.
Watch out. Mixing turns and radians is the usual slip. Change both to radians before using the equations.
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