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

AI Thread Summary
To determine the force needed to move a 50kg box up a 40-degree ramp with a 1m/s² acceleration and a pulling angle of 15 degrees, the equations of motion and friction were applied. The calculations involved breaking down the gravitational forces and normal force, leading to the equation F = 405.748 N. However, the physics teacher suggested the force should be around 356 N, prompting a review of the calculations. It was noted that potential errors could stem from miscalculating the signs or operations in the equations. The discussion emphasizes the importance of careful arithmetic in physics problem-solving.
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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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