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Homework Statement
Check out my attachment to get an idea what is happening. What we have is an inclined plane with 2 masses (m1 and m2) which are touching one another and the angle of the incline is 30 degrees.
The coefficient of kinetic friction between m1 and the plane is 0.23 = mu_k1
The coefficient of kinetic friction between m2 and the plane is 0.51 = mu_k2
m1 = 2.5kg
m2 = 3.1kg
theta = 30 degrees
The question is to find the acceleration of the pair of masses, and the second question is find the force of m1 on m2
Homework Equations
F=ma
The Attempt at a Solution
I applied Mr Newton on each mass individually to get
for mass m1:
x direction (parallel to the inclined plane):
[tex]F_{21}\mu_{k1}N_{1}+m_{1}g\sin(30)=m_{1}a[/tex]
y direction (perpendicular to the inclined plane):
[tex]m_{1}g\cos(30)+N_{1}=0[/tex]
for mass m2:
x direction:
[tex]F_{12}\mu_{k2}N_{2}+m_{2}g\sin(30)=m_{2}a[/tex]
y direction:
[tex]m_{2}g\cos(30)+N_{2}=0[/tex]
I used [tex]F_{12}=F_{21}[/tex].
I put all that into the mix and out popped a = 9.33m/s^2, which is wrong.
The answer says a = 1.6m/s^2. I am pretty sure my maths is ok. I'd say the problem is in my application of Newton but can't see anything wrong.
Thanks in advance
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