A freely falling body has attained a velocity of $2 \mathrm{~ms}^{-1}$. Now, if the weight of the body is…
A freely falling body has attained a velocity of $2 \mathrm{~ms}^{-1}$. Now, if the weight of the body is opposed by upward air resistance, then the total distance travelled before stopping is
$4 \mathrm{~m}$
$8 \mathrm{~m}$
$0.2 \mathrm{~m}$
$0.4 \mathrm{~m}$
Solution
Using conservation of momentum
$\begin{aligned} & m u=m\left(v_1+v_2+v_3\right) \\ & 0=\hat{i} v+\hat{j} v+v_3 \\ & \Rightarrow v_3=-\hat{i} v-\hat{j} v \\ & \left|v_3\right|=\sqrt{2} v\end{aligned}$