Q.

Let L→ and P→ represent the angular momentum and linear momentum respectively of a particle of mass 'm' having position vector r→=a(i^ cos ωt+j^ sin ωt). The direction of force is         [2025]

1 Opposite to the direction of r→  
2 Opposite to the direction of L→  
3 Opposite to the direction of P→  
4 Opposite to the direction of L→×P→  

Ans.

(1)

r→=a cos ωti^+a sin ωtj^

v→=dr→dt=–aω sin ωti^+aω cos ωtj^

a→=dv→dt=–aω2cos ωti^–aω2sin ωtj^

a→=–ω2(a cos ωti^+a sin ωtj^)=–ω2r→

a→ is antiparallel to r→

Hence, F→ is opposite to the direction of r→