Question

A flat car of mass $m_0$ starts moving to the right on a frictionless surface due to a constant horizontal force F at t=0. Sand spills on the flat car from a stationary hopper. The velocity of the loading is constant and is equal to $\mu$ kg s${}^{-1}$. Then,

• A. initial acceleration is equal to $\frac{F}{m_0}$
• B. acceleration at time t is $\frac{F}{(m_0+\mu t)}$
• C. initial acceleration is less than $\frac{F}{m_0}$
• D. none of these

Answer 1

Answer: (A), (B)

The correct options are
A initial acceleration is equal to $\frac{F}{m_0}$
B acceleration at time t is $\frac{F}{(m_0+\mu t)}$

At $t=0$, mass of the car = $m_o$

Force acting on it $=F$

Thus acceleration of the car at $t=0$, $a=\frac{F}{m_o}$