5.26 A stone of mass m tied to the end of a string revolves in a vertical circle of radius R. The net forces at the lowest and highest points of the circle directed vertically downwards are : [Choose the correct alternative]

Lowest Point                          Highest Point

(a) mg – T₁                                mg + T₂

 

(b) mg + T₁                                mg – T₂

 

(c) mg +T₁   – (m ${\mathit{v}}_1^2$ ) / R  mg – T₂+ (m ${\mathit{v}}_1^2$ ) / R

 

(d) mg – T₁   – (m ${\mathit{v}}_1^2$ ) / R  mg + T₂ + (m ${\mathit{v}}_1^2$ ) / R

 

T₁ and v₁ denote the tension and speed at the lowest point. T₂ and v₂ denote corresponding values at the highest point.

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