As disc like reel with massless thread unrolls itself while falling vertically downwards the acceleration of its fall is |
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a) |
g |
b) |
c) |
Zero |
d) |

As disc like reel with massless thread unrolls itself while falling vertically downwards the acceleration of its fall is |
||||||||

a) |
g |
b) |
c) |
Zero |
d) |

1 Answer

127 votes

**(d)**

Let be acceleration of fall of the thread, then net force acting downwards, balances the force due to tension in the thread.

…(i)

Also torque (also known as moment or couple acts on the system).

From Eq. (i),

…(ii)

Let is moment of inertia of reel and the angular acceleration, then torque is

…(iii)

where,

…(iv)

Equating Eqs. (ii) and (iv), we get

127 votes

127