A force F⃗=(40î+10ĵ) N acts on a body of mass 5 kg. If the body starts from rest, its position vector r⃗ at time t=10 s, will be

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(2) (400î+100ĵ) m. Idea: a constant force gives a constant acceleration, and from rest r⃗=1/2a⃗t² acts on each component separately. a⃗=(F⃗)/m=(40î+10ĵ)/5=8î+2ĵ m/s². r⃗=1/2a⃗t²=1/2(8î+2ĵ)(10)² =50(8î+2ĵ)=400î+100ĵ m. The 4:1 ratio of the force components survives untouched into the displacement, which is the quickest way to spot the right option.

A force F⃗=(40î+10ĵ) N acts on a body of mass 5 kg. If the body starts from rest, its position vector r⃗ at time t=10 s, will be

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