Acceleration/Tension between two masses

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In summary, the conversation discusses a physics problem involving force and friction that the speaker was struggling to understand. The problem involved finding the acceleration and tension between two masses. The professor used equations such as n-mg=0 and Force-Kinetic Friction-Tension = mass*acceleration to solve the problem. The final answers were an acceleration of 11.4 m/s2 and a tension of 26 N. The speaker mentions drawing free body diagrams and applying Newton's laws to solve the problem, and expresses difficulty in understanding the fundamentals of the process. The summary also includes advice to draw separate free body diagrams for each object and to note that the top and bottom objects have the same acceleration in opposite directions.
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kbru
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Homework Statement



I am currently taking a Summer physics course, and today we were given a Force/Friction problem that even after the professor explained, I could not fully understand.

https://de6d4c993829dd9a7ebe8c71bf32cb36b6fe5892.googledrive.com/host/0B79Pxd57IVb7aWU0Q3JqeG5XbjQ/FreeBodyFrictionPrblm.png

Mass of Objects: m1=5.0kg m2=2.0kg

Given Friction Valules: Mk1 (Between Block and Surface) = 0.20 Mk
Mk2 (Between Blocks) = 0.15

I am supposed to find acceleration, as well as the tension between the two masses.

Homework Equations



Equations that he used to solve the problem:

n-mg=0

Force-Kinetic Friction-Tension = mass*acceleration

The Attempt at a Solution



I was able to draw a free body diagram of the system, however, I only included 2 values for normal force and Kinetic Friction, where in his complete Free Body Diagram, there were 3 values for both. I really got lost when he solved the problem using a system of equations towards the end.

The acceleration ended up being 80/7 m/s2, or about 11.4 m/s2, and tension ended up being around 26 N.

I have been studying this topic, but I don't really understand the fundamentals of the whole process, and memorizing formulas hasn't helped whatsoever. Any guidance would be greatly appreciated!
 
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  • #2
kbru said:

Homework Statement



I am currently taking a Summer physics course, and today we were given a Force/Friction problem that even after the professor explained, I could not fully understand.

https://de6d4c993829dd9a7ebe8c71bf32cb36b6fe5892.googledrive.com/host/0B79Pxd57IVb7aWU0Q3JqeG5XbjQ/FreeBodyFrictionPrblm.png

Mass of Objects: m1=5.0kg m2=2.0kg

Given Friction Valules: Mk1 (Between Block and Surface) = 0.20 Mk
Mk2 (Between Blocks) = 0.15

I am supposed to find acceleration, as well as the tension between the two masses.

Homework Equations



Equations that he used to solve the problem:

n-mg=0

Force-Kinetic Friction-Tension = mass*acceleration

The Attempt at a Solution



I was able to draw a free body diagram of the system, however, I only included 2 values for normal force and Kinetic Friction, where in his complete Free Body Diagram, there were 3 values for both. I really got lost when he solved the problem using a system of equations towards the end.

The acceleration ended up being 80/7 m/s2, or about 11.4 m/s2, and tension ended up being around 26 N.

I have been studying this topic, but I don't really understand the fundamentals of the whole process, and memorizing formulas hasn't helped whatsoever. Any guidance would be greatly appreciated!
you should draw free body diagrams of each object separately. Identify all the forces acting on each object, and apply Newtons laws. All accelerations are with respect to the ground. Note that the top and bottom objects have the same acceleration but in opposite directions. And the cord tensions on each are the same. No acceleration in vert direction. Do not draw a free body of the blocks together...split them up.
 
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Related to Acceleration/Tension between two masses

1. What is acceleration between two masses?

Acceleration between two masses is the rate of change of velocity of an object due to the influence of another object's gravitational force. It is measured in meters per second squared (m/s²) and can be calculated using the formula a = F/m, where a is acceleration, F is the force between the two masses, and m is the combined mass of the two objects.

2. How does the tension between two masses affect acceleration?

The tension between two masses is an external force that can impact the acceleration of the objects. In a situation where one mass is pulling on the other with a string, the tension force will be equal to the force of gravity on the smaller mass. This will result in the smaller mass accelerating towards the larger mass at a rate determined by the formula a = F/m. If the tension force is greater than the force of gravity, the smaller mass will accelerate towards the larger mass at a faster rate.

3. Can the acceleration between two masses be negative?

Yes, the acceleration between two masses can be negative. This occurs when the direction of the acceleration is opposite to the direction of the force. For example, if one mass is pulling on the other with a string and the larger mass is moving away from the smaller mass, the acceleration will be negative because the force is pulling in the opposite direction of the motion.

4. How do the masses of the objects affect the acceleration between them?

The masses of the objects have a direct impact on the acceleration between them. According to Newton's Second Law of Motion, the acceleration of an object is directly proportional to the force applied on it and inversely proportional to its mass. This means that the larger the mass, the smaller the acceleration will be for a given force, and vice versa.

5. Is there a maximum acceleration that can occur between two masses?

There is no maximum acceleration that can occur between two masses. As long as there is a force acting between the two masses, there will be an acceleration. However, as the distance between the two masses increases, the force of gravity decreases and the acceleration will also decrease. Additionally, external factors such as friction and air resistance can also impact the acceleration between two masses.

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