Rotation of two contact bodies

Easy Math Editor

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Math	Appears as
Remember to wrap math in `$` ... `$` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$

Comments

@Steven Chase Sir i got the answer for 1st part , but for second and third part i am not getting correct one pls see.

Kudo Shinichi - 1 year, 9 months ago

What are the expected answers? For 38, I don't see why there would be any force.

Steven Chase - 1 year, 9 months ago

Why would there be no force @Steven Chase sir (will not there be centripetal accleration ?), as such u r correct for 38 , given its D and for last one B

Kudo Shinichi - 1 year, 9 months ago

@Kudo Shinichi – The center of mass is not accelerating, and the rotation speed is constant. So there can't be any net force or torque.

Steven Chase - 1 year, 9 months ago

@Steven Chase – @Steven Chase sir , what about the centripetal force which leads to the rotation at constant angular velocity? By drawing FBD of smaller cylinder there needs to be a force which would provide centripetal force isn't?

Kudo Shinichi - 1 year, 9 months ago

@Kudo Shinichi – @Steven Chase sir , am i telling something wrong ?

Kudo Shinichi - 1 year, 9 months ago

@Kudo Shinichi – For each infinitesimal portion of the small cylinder, there is a centripetal force. But there is another infinitesimal portion on the opposite side which requires an equal and opposite force. So the net external force is zero. As I said before, the center of mass is not accelerating, and the rotational speed is not changing. So there can't be any net external force on the small cylinder in number 38

Steven Chase - 1 year, 9 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$