A uniform disc of radius R and mass M is free to rotate only about its axis. A string is wrapped over its…

A uniform disc of radius R and mass M is free to rotate only about its axis. A string is wrapped over its rim and a body of mass m is tied to the free end of the string as shown in the figure. The body is released from rest. Then the acceleration of the body is:

  1. 2 Mg2m+M
  2.  2 Mg2M+m
  3. 2 mg2M+m
  4. 2 mg2m+M

Solution

mg-T=ma

RT=Iα

RT=MR22 .aR

T=Ma2

mg-Ma2= ma

mg=aM2+m

mg=a M+2m2

a=2mgM+2m

Asked in: JEE Main 2017 (08 Apr Online)

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