Question

a truck moving on a smooth horizontal surface with a uniform speed v caries stone dust. if the mass dm dust from the stone in time dt, force needed to keep the truck moving with uniform speed in horizontal direction is
a v*dm/dt
b zero
c m*dv/dt
​d dm*dt/v

Answer 1

Here the stone of mass dm is leaked out in time dt.

The force exerted on the truck due to leaking stone dust is given by,u∆m∆t in the vertically upward direction. Since there is no friction, thus, no force is needed to keep the truck moving with a constant speed in the horizontal direction.