Q120 / 200 · NEET 2008 (Screening) · Physics
Sand is being dropped on a conveyor belt at the rate of $M \mathrm{~kg} / \mathrm{s}$. The force necessary to keep the belt moving with a constant velocity of $v \mathrm{~m} / \mathrm{s}$ will be
- Correct answerA$M v$ newton
- B$2 M v$ newton
- C$\frac{M v}{2}$ newton
- Dzero
Solution
Force required,
$\begin{aligned}
F & =\frac{d(m v)}{d t} \\
& =v\left(\frac{d m}{d t}\right)=v M
\end{aligned}$
as velocity $v$ is constant, hence
$F=M v \text { newton }$
Hence, the correct answer is option: 'A'.