How to Solve for Force Needed to Move a Box on a Ramp with Kinetic Friction

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SUMMARY

The discussion focuses on calculating the force required to move a 50 kg box up a ramp inclined at 40 degrees, with an acceleration of 1 m/s² and a pulling angle of 15 degrees above the ramp. The frictional constant is given as 0.1. The user derived the equations using Newton's second law (F=ma) and the frictional force equation (F=(mu)N), ultimately calculating the force (F) to be approximately 405.748 N. However, discrepancies arose as the physics teacher suggested the force should be around 356 N, indicating potential errors in sign or arithmetic during calculations.

PREREQUISITES
  • Understanding of Newton's second law (F=ma)
  • Knowledge of frictional forces and coefficients (mu)
  • Ability to resolve forces into components
  • Familiarity with free body diagrams (FBD)
NEXT STEPS
  • Review the principles of vector resolution in physics
  • Study the effects of friction on inclined planes
  • Learn about the significance of angles in force calculations
  • Practice solving similar problems involving forces on ramps
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and force analysis, as well as educators looking to clarify concepts related to forces on inclined planes.

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Homework Statement


Find the force(F) needed to move a 50kg box up a ramp angled at 40 degrees with an acceleration of 1m/(s^2) while pulling at an angle of15 degrees above parallel to the ramp. the ramp has a frictional constant of .1
a=1m/(s^2)
m=50kg
angle of ramp=40 degrees
angle pulling box at = 15 degrees
mu(sub k) = .1
g(gravity)=9.8

Homework Equations


F=ma
F=(mu)N


The Attempt at a Solution


i drew a fbd then split things up into components and found m*g*cos(40)=375.362 and m*g*sin(40)=314.966
then to find force i combined the vectors and equations

50 = F*cos(15) - (314.966 + .1N)
N= -F*sin(15) + 375.362

from here i solved for F by plugging in for N since i had the same two variables in each equation.

50 = F*cos(15) - (314.966 + .1((-F*sin(15)) + 375.362))
50 = .966F - (314.966 -0.026F + 37.536)
402.502 = .992F
F = 405.748
now i solved this however my physics teacher said that F is around 356 but i am unable to find my mistake and was wondering if someone could help me
 
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It looks like all of your math checks out to me. I think your physics teacher may have gotten his signs mixed up somewhere. I don't see where you could have gotten a magically different number.
 
Edit to may above post: Your teacher could have accidentally done 314.966-37.536 instead of addition. Then it end up around 348.33, which is just a difference in rounding.
 

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