Question

please solve the problem

Answer 1

We know that F = ma + u(dm/dt)
Here a = 0
Hence substituting the values we get F = 100/60 = 1.67 N

Answer 2

M= mass = 500 kg
v = velocity = 10 m/s Δm = 10 kg/min = 1/6  kg/sec
The 500 kg truck is moving with uniform speed. So there is no force required to maintain its speed.So in Δt = 1 sec. 1/6 kg of sand is added.
The momentum that is to be imparted to 1/6 kg of sand, so that it gains from 0 velocity to 10 m/s = Δp = 1/6 kg * 10 m/s = 5/3 kg-m/s
additional force required is Δp÷Δt = 5/3 N