Sand falls onto a conveyor belt at mass rate M kg s⁻¹. Find the horizontal force necessary to keep the belt moving steadily at speed v m s⁻¹.
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Question

Sand falls onto a conveyor belt at mass rate M kg s⁻¹. Find the horizontal force necessary to keep the belt moving steadily at speed v m s⁻¹.

G1 Physics · Accepted Answer

Sand arrives with zero horizontal velocity and must acquire the belt speed v. Momentum added per unit time = (mass flow rate)×(velocity change)=Mv. Therefore the belt must supply horizontal force Mv N. Answer: A.