Laws Of Motion Question 418
Question: A truck moving on a smooth horizontal surface with a uniform speed u is carrying dust. If a mass $ \Delta m $ of the dust leaks from the truck in vertical downward direction in time $ \Delta t, $ the force needed to keep the truck moving at its constant speed is
Options:
A) Zero
B) $ \frac{u\Delta m}{\Delta t} $
C) $ \Delta m\times \frac{du}{dt} $
D)$ u\frac{\Delta m}{\Delta t}+\Delta m\times \frac{du}{dt} $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] The force exerted on the truck due to leaking of dust is in
$ \frac{\Delta m}{\Delta t} $ vertical upward direction.
Since, there is no friction, no horizontal force acts on the truck, hence no forcer is required to keep its uniform motion intact.
