What is the momentum of the box at the bottom?

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Homework Help Overview

The problem involves calculating the momentum of a box sliding down an incline, taking into account gravitational potential energy, kinetic energy, and frictional forces. The box has a weight of 98.0 N and slides 25.0 m along a 35.0° incline, starting from rest.

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Approaches and Questions Raised

  • The original poster attempts to apply energy conservation principles but questions their calculation after comparing with a provided answer. Some participants suggest that the energy lost to friction was not considered in the original calculation.

Discussion Status

Participants are exploring different aspects of the problem, including the impact of friction on energy conservation. There is an indication that some have made progress in understanding the relationship between potential energy, kinetic energy, and frictional forces, but no consensus has been reached.

Contextual Notes

There is a mention of a specific answer from a textbook, which may influence the discussion. The original poster's calculations may be constrained by assumptions regarding energy loss due to friction, which is being questioned by others.

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A 98.0 N box slides 25.0 m along a 35.0° incline. If the force of friction along the incline is 32.0 N, and the box starts from rest at the top, what is the momentum of the box at the bottom?

This is how i attempted to solve this question. :confused: The answer in the book is 1.1 * 10^2 Kgm/s. Can you please tell me what error i have made. Thank-you.

Eptop + Ektop = Epbot + Ekbot
mgh + 0 = 1/2mv^2 + 0
(9.81m/s^2)(25.0m*Sin35) = 1/2v^2
v=16.77 m/s

Fg=mg
m=98.0 N/9.81m/s^2
m=9.9898 Kg

p=mv
p=(9.9898 Kg)(16.77 m/s)
p=168 Kgm/s
 
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You didn't take into account the energy lost to friction.
 
Lol shaani nu gaal kadh :wink:
 
i think i figured it out:

Ep=Ek + Ffd
mgh=1/2mv^s + Ffd

THen solve for v and use that in p=mv
 

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