Atwood machine with two ropes on one of the blocks

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SUMMARY

The discussion focuses on solving a physics problem involving an Atwood machine with two blocks connected by a pulley system. Block 1 has a mass of 20 kg and Block 2 has a mass of 10 kg, with a coefficient of friction of 0.1 and an incline angle of 12 degrees. Key equations include Fnet = ΣF = ma, N = mFgcosθ, and fk = μkN. The user seeks assistance in determining the acceleration of both blocks and the tension in the rope, while also correcting errors in their initial force equations.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with force diagrams and free-body diagrams
  • Knowledge of frictional forces and their calculations
  • Basic trigonometry for resolving forces on an incline
NEXT STEPS
  • Review the derivation of net force equations in pulley systems
  • Study the principles of tension in Atwood machines
  • Learn about the effects of friction on inclined planes
  • Practice solving similar physics problems involving multiple blocks and pulleys
USEFUL FOR

Students studying physics, particularly those focusing on mechanics, as well as educators looking for examples of problem-solving in dynamics involving pulleys and friction.

physiccs
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Homework Statement


Block 2 has a mass of 10kg and is attached to a pulley. The string going through the pulley is fixed to a bar on one end. The other end of the string goes over a pulley and a cylinder, of mass 20kg hangs on the string. The coefficient of friction between block 2 and the surface is 0.1 and the angle is 12 degrees.

a) Draw force diagrams for the block and the cylinder.
b) Write the net force equation for the cylinder.
c) Write the net force equation for the block.
d) What is the acceleration of the block and the cylinder?
e) What is the tension in the rope?

https://docs.google.com/drawings/d/synEJ44IbHB9hEywEOJvHjw/image?w=370&h=129&rev=1&ac=1

Variables:
m1 = 20 kg
m2 = 10 kg
μk = 0.1
θ = 12°

Homework Equations


Fnet = ΣF = ma
N = mFgcosθ
fk = μkN

The Attempt at a Solution


a) On block 1, tension pulls up and the force of gravity pulls straight down with a force greater than that of the tension. On block 2, there are two tension forces (one for the rope on each side of the pulley) pulling parallel to the incline upwards, friction in the opposite direction of the tension forces, the normal force pulling up and at an angle perpendicular to the plane's surface, and the force of gravity pulling straight down.
b) Fnet cylinder = Fg - T
= m1g - m1a
c) Fnet block = T1 + T2 - Ffk - Fgsinθ
= m2a/2 + m2a/2 - μFgcosθ - Fgsinθ
= m2a/2 + m2a/2 - μm2gcosθ - m2gsinθ
d) acylinder = ablock/2

I would love to continue with this attempt at a solution, but I honestly do not know where to go from here... I am not even sure if my belief that the acceleration of block 1 is twice that of block 2. Basically, I am completely stuck, and I have no idea on how to go about solving for the acceleration of either block. Obviously, any help is very much appreciated. Thank you so much!
 
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physiccs said:
b) Fnet cylinder = Fg - T
= m1g - m1a
The second line is wrong. Think about it again.
c) Fnet block = T1 + T2 - Ffk - Fgsinθ
= m2a/2 + m2a/2 - μFgcosθ - Fgsinθ
Same error as before. You are equating ma with T in each case. What should you equate ma to?
 

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