1.

A uniform force of `(3 hat(i)+hat(j))` newton acts on a particle of mass `2 kg`. Hence the particle is displaced from position `(2 hat(i)+hat(j))` meter to position `(4 hat(i)+ 3hat(j)-hat(k))` meter. The work done by the force on the particle is `:`A. ` 15 J`B. `9 J`C. `6 J`D. `13 J`

Answer» Correct Answer - B
Here, `vec(F)=(3hat(i)+hat(j))N`
`vec(r)=vec(r_(2))-vec(r_(1))=(4hat(i) +3 hat (j) -k)-(2hat(i)+hat(k))`
`=(2hat(i)+3hat(j)-2hat(k))`
`W=vec(F).vec(r)=(3hat(i)+hat(j)).(2hat(i)+3hat(j)-2hat(k))`
`W=6+3=9J`


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