Why is it assumed that angular acceleration is 0 when a ball is midair after rolling off a surface with constant velocity?
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$\begingroup$ Rolling w/o slipping? $\endgroup$– GertCommented Jul 30, 2020 at 21:30
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$\begingroup$ Hello Deen, welcome to Physics StackExchange. I would suggest in the future you try to show some of your own effort to try to solve the problem. This could be useful for other users to give more helpful answers. $\endgroup$– Ivan BurbanoCommented Jul 30, 2020 at 21:45
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1 Answer
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Forces acting on each point of the sphere (or any object) due to gravity are the same everywhere when the object is in free fall. Therefore, the net external torque is $0$
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$\begingroup$ Air drag is going cause a small torque that reduces the rotational speed. Of course it could be other way around where the turbulence on one side may cause the ball to rotationaly accelerate. $\endgroup$– jalexCommented Jul 30, 2020 at 21:59