Calculating the Impact of Sand on a Dump Truck's Weight

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The discussion focuses on calculating the additional weight reading on a scale due to sand being dumped into a stationary truck. The key points include the mass of sand falling at 55kg per second from a height of 2.0m, which affects the net force and weight reading on the scale. The participant attempts to apply relevant physics equations, including momentum and force calculations, to determine the excess weight reading. Feedback emphasizes the importance of considering the sand's momentum rather than the truck's weight in the calculations. The conversation highlights the complexities of mechanics and the need for accurate application of formulas.
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Hello,

i'd like to run my reasoning by someone for a mechanics question. I've not been well, so have missed a few sessions where the material was covered - this is (part of) my attempt to catch up.

Homework Statement



A dump truck is being filled with sand. The sand falls straight down from a rest height of 2.0m above the truck bed, and the mass of sand hitting the truck per second is 55kg. The truck is parked on the platform of a weigh scale. By how much does the scale reading exceed the actual weight of the truck and sand?

Homework Equations


3. The Attempt at a Solution [/b

The truck and sand has a w = mg, but am artificial reading is given due to the net force of the sand pouring into the truck.

p = mv

a = (vf - vi / Δt)

Ʃf = ma

Ʃf = m(vf - vi / Δt)

= (mvf - mvi) / ΔtSince the sand starts at rest, Ʃf = mvf / Δt

I can use v2 = u2 + 2as to find the sands velocity and plug it into the above. And then the force is by how much the weight reading exceeds the weight of the truck and sand.

I hope that's correct, but mechanics isn't my strong suit.

Thanks for taking a look!
 
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Your formulae appear to outline the correct approach to the answer. But it won't be if you are using m as the weight of the truck.
 
NascentOxygen said:
Your formulae appear to outline the correct approach to the answer. But it won't be if you are using m as the weight of the truck.

It's the sand that provides the extra force, so it's the sands momentum I'm interested in.

Thanks for the feedback.
 
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