Question

11. Sand drops from a stationary hopper at the rate of 5 kgs onto a conveyor belt moving with
constant speed of 2 m/s. What is the force required to keep the belt moving and what is the
delivered by the motor moving the belt? (Impulse J = Ft = mv)
a) 10 N, 20 W b) 20 N, 10 W
c) 10 N, 10 W
d) 20 N, 20 W​

Answer 1

Answer:

a) 10 N, 20 W

Explanation:

Here mass of sand drops at a rate of 5kg/s

⟹dtdm=5kg/s

Velocity of conveyor belt , v=2 m/s

Force required to keep th ball moving , F=dtd(mv)=vdtdm=5×2=10 N

Power  delivered by the motor ,P=F⋅v=10×2=20 W

Answer 2

Explanation:

Here mass of sand drops at a rate of 5kg/s

⟹  

dt

dm

​  

=5kg/s

Velocity of conveyor belt , v=2 m/s

Force required to keep th ball moving , F=  

dt

d

​  

(mv)=v  

dt

dm

​  

=5×2=10 N

Power  delivered by the motor ,P=F⋅v=10×2=20 W