- #1
Tepictoc
- 16
- 0
Homework Statement
I have a box on a horizontal plane.
Given data: mass = 0.25kg
height of object = 14 cm
width of object = 9cm
Calculate the coefficient of static friction.
Homework Equations
μs = Ff/N (N is the normalforce)
F = Ff = μ*N
mg = 2.45 Newton
The Attempt at a Solution
I apply an unknown force on the object from the left side at the height of x to see where it starts to tip over instead of slide. Looks like it's at 13 cm. x = 13
The vertical forces:
N cancels out mg since the object is not accelerating up or down, so N=mg.
μk is irrelevant in this case so I'll just write μ when I mean μs.
The horizontal forces:
Ff is acting in the opposite direction of the applied Force
F = Ff = μ*N
L is the length to the middle 4.5cm
mg*L - F*x = 0
I substitute in μ*mg instead where F*x is
mg*L - μ*mg = 0
This is where I think I might be going wrong:
μ = mg*L/mg
μ = L
Which would mean the coefficient of static friction is 4.5 or 0.45 which is too high.
When I angle (at 12 degrees) the same object on the same surface and calculate the μs it became 0.21
If I go this way it's slightly better but probably wrong since one m disappears:
μ = mg*L/g = 0.24