Atwood machine with two ropes on one of the blocks

In summary, the problem involves a pulley system with two blocks, one with a mass of 10kg and one with a mass of 20kg, and a coefficient of friction of 0.1. The force diagrams for both blocks include tension, force of gravity, normal force, and friction. The net force equations for the cylinder and block involve these forces and their components. The acceleration of the blocks can be determined by equating the net force equations to ma. The tension in the rope can be solved for by considering the forces acting on the blocks.
  • #1
physiccs
1
0

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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  • #2
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?
 

Related to Atwood machine with two ropes on one of the blocks

1. How does an Atwood machine with two ropes on one of the blocks work?

An Atwood machine with two ropes on one of the blocks is a simple mechanical device used to demonstrate the principles of pulleys and the laws of motion. It consists of two blocks connected by a rope that passes over a pulley. One block is heavier than the other, and the difference in weight causes the system to move. The heavier block will accelerate downwards while the lighter block will accelerate upwards.

2. What are the main components of an Atwood machine with two ropes on one of the blocks?

The main components of an Atwood machine with two ropes on one of the blocks include two blocks, a pulley, and a rope. The blocks are connected by the rope, which passes over the pulley. The pulley serves to change the direction of the force and distribute the weight of the blocks evenly.

3. What is the purpose of using two ropes on one of the blocks in an Atwood machine?

The use of two ropes on one of the blocks in an Atwood machine allows for a greater difference in weight between the two blocks. This results in a larger acceleration and makes it easier to observe the effects of the system.

4. How does the acceleration of an Atwood machine with two ropes on one of the blocks change with different weight ratios?

The acceleration of an Atwood machine with two ropes on one of the blocks is directly proportional to the difference in weight between the two blocks. As the weight ratio increases, the acceleration also increases. However, if the weight ratio is equal (i.e. both blocks have the same weight), the system will be in equilibrium and there will be no movement.

5. What are some real-life applications of an Atwood machine with two ropes on one of the blocks?

An Atwood machine with two ropes on one of the blocks can be used to demonstrate the principles of mechanical advantage and pulleys. It is also used in various industries, such as construction and transportation, for lifting and moving heavy objects. In addition, it serves as a basis for understanding more complex systems, such as elevators and cranes.

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