Question:
A body with mass 5 kg is acted upon by a force
$F=(-3 \hat{i}+4 \hat{j})$ N. If its initial velocity at $\mathrm{t}=0$ is
$v=(6 \hat{i}-12 \hat{j}) \mathrm{m} / \mathrm{s}$, the time at which it will just have a velocity along the $\mathrm{y}$-axis is
(a) never
(b) 10 s
(c) 2 s
(d) 15 s
Solution:
The correct answer is (b) 10 s