Question

An object of mass $2\, kg$ at rest at origin starts moving under the action of a force
$\vec{F}=\left(3 t^{2} \hat{i}+4 \hat{t}\right) N$
The velocity of the object at $t=2\, s$ will be

• A. $(3 \hat{i}+2 \hat{j}) m / s$
• B. $(2 \hat{i}+4 \hat{j}) m / s$
• C. $(4 \hat{i}+4 \hat{j}) m / s$
• D. $(3 \hat{i}-4 \hat{j}) m / s$

Answer 1

Answer: (C)

$\vec{F}=3 t^{2} \hat{i}+4 t \hat{j}$
$P_{2}-P_{1}=\frac{3 t^{3}}{3} \hat{i}+\frac{4 t^{2}}{2} \hat{j}$
$P_{1}=0$
$(2) v=(2)^{3} \hat{i}+2(2)^{2} \hat{j}$
$v=4 \hat{i}+4 \hat{j}$