# 3 blocks dragging with friction, find tension

In summary, the problem involves three blocks connected by a massless cord and pulled to the right with a force of 82.0 N. The masses of the blocks are 3.0 kg, 5.0 kg, and 6.0 kg. The coefficient of kinetic friction between the blocks and the table is 0.126. Using Newton's second law, the acceleration of the system is calculated to be 4.62234 m/s^2. However, the attempted solution for finding T2 is not correct as it does not consider the friction force on M3. A correct solution would involve drawing a free body diagram for M3 and using the equation T2 - Fk = (M1+M2

## Homework Statement

Three blocks are located on a horizontal table. The coefficient of kinetic friction between the blocks and the table is 0.126. They are connected by a massless cord, as shown in the figure below, and pulled to the right. The masses of the three blocks are m1 = 3.0 kg, m2 = 5.0 kg, and m3 = 6.0 kg. The pulling force is equal to T3 = 82.0 N. What is the tension T2?

F=ma

## The Attempt at a Solution

I am just plain clueless

It's F_net = ma, per Newton's 2nd law. Look at all 3 blocks together (they move and accelerate together) , and apply Newton 2 to the system of blocks to calculate the acceleration. Then, to get T2, the cord tension pulling back on m3, you must learn how to draw free body diagrams. Isolate block m3 to denote the forces acting on it. Then apply Newton 2 again. Please show an attempt.

Okay so to get acceleration for the whole system, I found all the frictional forces of the blocks and added them up (17.2872N) and subtracted them all by the pulling force (82.0N) and took the mass of all the blocks together and solved for a.

(82.0-17.2872)=14.0a

a=4.62234m/s^2

Is this acceleration right?

So i now have the a=4.62m/s^2 and the frictional force is 17.29N. I don't know if this is right but I used: T2-Fk=(M1+M2)(a) so T2=(M1+M2)(a)+Fk or with numbers T2=(3+5)(4.62)+17.29 and I got T2=54.25N is this right?

Okay so to get acceleration for the whole system, I found all the frictional forces of the blocks and added them up (17.2872N) and subtracted them all by the pulling force (82.0N) and took the mass of all the blocks together and solved for a.

(82.0-17.2872)=14.0a

a=4.62234m/s^2

Is this acceleration right?
Looks good!
So i now have the a=4.62m/s^2 and the frictional force is 17.29N. I don't know if this is right but I used: T2-Fk=(M1+M2)(a) so T2=(M1+M2)(a)+Fk or with numbers T2=(3+5)(4.62)+17.29 and I got T2=54.25N is this right?
Good effort, but not correct. It looks like you took a free body diagram (FBD)of the first 2 blocks, which is fine...but the friction force is the sum of the friction forces on M1 and M2. Do not include the friction force on M3; it doesn't show up in your FBD of the first 2 blocks.

## What is the concept of "3 blocks dragging with friction, find tension"?

The concept refers to a problem in physics where three blocks are connected by a rope and are being dragged over a surface with friction, and the task is to find the tension in the rope.

## What are the factors that affect the tension in this scenario?

The tension is affected by the weight of the blocks, the coefficient of friction between the blocks and the surface, and the force applied to drag the blocks.

## How can the coefficient of friction be determined in this scenario?

The coefficient of friction can be determined by dividing the force of friction by the normal force, which is the weight of the blocks in this case.

## What is the role of Newton's laws of motion in solving this problem?

Newton's laws of motion, specifically the second law, can be used to calculate the net force acting on the blocks and determine the tension in the rope.

## What are some real-life applications of this problem?

This problem can be seen in situations where multiple objects are connected and are being dragged or pulled, such as a car towing a trailer or a person pulling a sled. It is also relevant in industries where heavy objects need to be moved with ropes or cables.

• Introductory Physics Homework Help
Replies
9
Views
1K
• Introductory Physics Homework Help
Replies
17
Views
1K
• Introductory Physics Homework Help
Replies
14
Views
1K
• Introductory Physics Homework Help
Replies
23
Views
1K
• Introductory Physics Homework Help
Replies
4
Views
2K
• Introductory Physics Homework Help
Replies
5
Views
2K
• Introductory Physics Homework Help
Replies
3
Views
1K
• Introductory Physics Homework Help
Replies
5
Views
1K
• Introductory Physics Homework Help
Replies
2
Views
4K
• Introductory Physics Homework Help
Replies
11
Views
2K