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

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In summary, the conversation discusses a mechanics question involving a dump truck being filled with sand and the resulting weight on a weigh scale. The person asking the question is trying to catch up on missed material and presents their attempt at a solution, using various equations to calculate the force of the sand and the excess weight on the scale. The other person provides feedback, clarifying that the weight of the truck should not be used in the calculations as it is the sand that provides the extra force.
  • #1
BOAS
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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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  • #2
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.
 
  • #3
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.
 

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

What is checking mechanics reasoning?

Checking mechanics reasoning is a process of evaluating the logical and mathematical steps used to solve a problem or reach a conclusion in the field of mechanics. This involves examining the assumptions, equations, and calculations used to ensure they are accurate and follow the principles and laws of mechanics.

Why is it important to check mechanics reasoning?

It is important to check mechanics reasoning because errors in logical or mathematical reasoning can lead to incorrect solutions and conclusions. In the field of mechanics, even minor mistakes can have significant consequences in terms of safety and functionality. Therefore, checking mechanics reasoning is crucial for ensuring the accuracy and reliability of results.

What are the common methods used for checking mechanics reasoning?

The common methods used for checking mechanics reasoning include dimensional analysis, unit conversions, and estimation. Dimensional analysis involves checking the dimensions of all quantities used in a problem to ensure they are consistent throughout the calculations. Unit conversions involve converting all quantities to a common unit to avoid errors and inconsistencies. Estimation involves approximating the expected result to determine if the calculated answer is reasonable.

When should one check mechanics reasoning?

One should check mechanics reasoning at every stage of problem-solving, from setting up the problem to reaching the final solution. This ensures that any errors or mistakes can be identified and corrected early on, rather than waiting until the end and potentially having to redo the entire calculation. Additionally, it is a good practice to check mechanics reasoning before submitting any results or conclusions.

What are the consequences of not checking mechanics reasoning?

The consequences of not checking mechanics reasoning can vary depending on the severity of the error. In some cases, it may lead to incorrect solutions or conclusions, which can have serious consequences in terms of safety and functionality. It can also result in wasted time and resources if the error is not caught until later on. Additionally, not checking mechanics reasoning can reflect poorly on the credibility and competence of the scientist or engineer.

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