Q.

Which of the following are correct expressions for torque acting on a body

A. τ→=r→×L→                               B. τ→=ddt(r→×p→)

C. τ→=r→×dp→dt                            D. τ→=Iα→

E. τ→=r→×F→

(r→ = position vector; p→ = linear momentum; L→ = angular momentum;

α→ = angular acceleration; I = moment of inertia; F→ = force; t = time)

Choose the correct answer from the options given below:          [2025]

1 B, D and E Only  
2 C and D Only  
3 B, C, D and E Only  
4 A, B, D and E Only  

Ans.

(3)

τ→=r→×L→                          wrong

τ→=ddt(r→×p→)               correct

τ→=r→×dp→dt=r→×F→       correct

τ→=Iα→                                  correct

τ→=r→×F→                            correct