- #1
jake010
- 12
- 2
- Homework Statement
- Find the magnitude and direction of the frictional force applied at point P if the system is to be in equilibrium.
- Relevant Equations
- m= 0.2 kg
M= 1.5 kg
r= 0.1 m
R= 0.3 m
g = 10 m/s^2
friction in axle and pulley, and mass of spokes and pulley are negligible
Correct answer: Fr = 5N
The figure is in the attached image.
My attempt:
I(wheel-disk system) = 0.5mr^2 + MR ^2
= 0.5(0.2kg)(0.1m)^2 + (1.5kg)(0.3m)^2
= 0.136(kg)(m^2)
Fnet(of object) = Ma
Mg - T = Ma
T = Mg - Ma
Fnet (wheel-disk system) = (M+m)a
Mg- Ma - Fr = (M+m)a
a = 0 because system in equilibrium
Mg - Fr = 0
Fr = Mg
Fr = 15N
This answer is incorrect, the correct answer is 5N and I'm not sure what I'm doing wrong.
My attempt:
I(wheel-disk system) = 0.5mr^2 + MR ^2
= 0.5(0.2kg)(0.1m)^2 + (1.5kg)(0.3m)^2
= 0.136(kg)(m^2)
Fnet(of object) = Ma
Mg - T = Ma
T = Mg - Ma
Fnet (wheel-disk system) = (M+m)a
Mg- Ma - Fr = (M+m)a
a = 0 because system in equilibrium
Mg - Fr = 0
Fr = Mg
Fr = 15N
This answer is incorrect, the correct answer is 5N and I'm not sure what I'm doing wrong.