Q.

A stone of mass 1 kg is tied to the end of a massless string of length 1 m. If the breaking tension of the string is 400 N, then the maximum linear velocity the stone can have without breaking the string, while rotating in a horizontal plane, is            [2023]

1 20 ms-1  
2 40 ms-1  
3 400 ms-1  
4 10 ms-1  

Ans.

(1)

Tcosθ=mg and Tsinθ=mv2l2sinθ

cosθ=mgT                     ...(i)

sin2θ=mv2Tl2                  ...(ii)

From (i) and (ii):  l=(mgT)2+mv2Tl2

l=(10400)2+v2400

 v=20m/s