defence exam Coast Guard Navik GD (General Duty) 02/2025 Mock Test Series Physics Center of Mass and Linear Momentum Centre of mass
A freight car moving with a uniform velocity v receives sand from a stationary hopper that falls at the rate \(\frac{dm}{dt} \). What is the force needed to keep the freight car moving at speed v ?
1
\( F = v \frac{dm}{dt} \)
2
\(F = \frac{v^2}{1+v}\frac{dm}{dt} \)
3
\(F = \frac{v^2}{1-v}\frac{dm}{dt} \)
4
0