Acceleration and Tension of two masses on an inclined plane with friction.

[Imuell1]

1. The problem statement, all variables and given/known data
In the attachment there is a drawing of the situation.
Mass one = 4kg and Mass two = 5kg
The coefficient of friction between mass one and the inclined plane = 0.24
Find the magnitude of the acceleration of the masses and the tension in the cord.



2. Relevant equations
Fk= μkFnormal
Fnetx=Mg*Sinϑ-Fk=Ma
Fnormal=Mg*Cosϑ

Fnetx=Fk+Mg*Sinϑ-T=Ma ???

3. The attempt at a solution

a=(Sinϑ-μkCosϑ)g.... a=9.8(Sin30-0.24*Cos30)=2.86m/s2
t=MgSinϑ-MgCosϑ*μk-Ma... t=33.9481-8.1476-14.3=11.5N


I'm not sure if the equation I ended up with for acceleration is correct and I am pretty sure that my equation for tension is completely wrong.

The book is giving me the answers a=2.4m/s/s and t=37N

[Imuell1]

bump

[Kruum]

Fnetx=Mg*Sinϑ-Fk=Ma
Fnetx=Fk+Mg*Sinϑ-T=Ma


How can this be?


a=(Sinϑ-μkCosϑ)g.... a=9.8(Sin30-0.24*Cos30)=2.86m/s2
t=MgSinϑ-MgCosϑ*μk-Ma... t=33.9481-8.1476-14.3=11.5N


What you're doing here is calculating an acceleration of a system that has a gravity towards sky. And using the acceleration from that to determine the tension of a completely different system.

Hint: Your completely ignoring the hanging mass. You can use it to your advantage.

[Phyzicslearn]

Awesome this helped me a lot. GOD bless you all.