Calculating Acceleration of M1,M2 System w/ Friction

In summary: I'll try again and see if I get the right answer. Thank you so much for your help and for taking your time to explain it to me. It really means a lot.Thank you so much I'm pretty sure that I got it now. I'll try again and see if I get the right answer. Thank you so much for your help and for taking your time to explain it to me. It really means a lot.In summary, the conversation discusses a physics problem involving a 500 g block on a horizontal tabletop connected to a 300 g block via a massless string and a frictionless pulley. The coefficient of kinetic friction is given and the system is released from rest. The conversation covers using Newton's Second Law to
  • #1
Cglez1280
21
0

Homework Statement


A 500 g block lies on a horizontal tabletop. The coefficient of kinetic friction between the block and the surface is 0.25. The block is connected by a massless string to the second block with a mass of 300 g. The string passes over a light frictionless pulley. The system is released from rest.
A. Use Newton's second law to write an equation for the 500 g mass
B. Use Newton's second law to write and equation for the 300 g mass
C. Find the acceleration of the system by simultaneously solving the system of two equations.
D. What is the tension force in the string?

M1= 500g
M2= 300g
Coefficient of friction=0.25

Homework Equations


I don't know at the moment

The Attempt at a Solution


So I've answered A and B.
For A I got Ft-Ffr=M1A
For B I got Ft-M2G=M2A
Part C is where I'm completely confused and me help with. I don't really understand how to do that
 
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  • #2
Cglez1280 said:
Part C is where I'm completely confused and me help with. I don't really understand how to do that
you have two equations of motion for the two connected masses.
part C asks you to simultaneously solve for acceleration of the system...
so it must be that the solution should satisfy the two equations...why not substitute result of one in the second so that the second one is also satisfied...
ask a question- should the acceleration of the two masses be same or different?
 
  • #3
drvrm said:
you have two equations of motion for the two connected masses.
part C asks you to simultaneously solve for acceleration of the system...
so it must be that the solution should satisfy the two equations...why not substitute result of one in the second so that the second one is also satisfied...
ask a question- should the acceleration of the two masses be same or different?
The acceleration for the two should be the same I think. This is summer work and my physics teacher gave me the answers and I have to work for the answers. The answer is 2.1 m/s^2
 
  • #4
Cglez1280 said:
The acceleration for the two should be the same I think.

the same string is connected passingthrough a frictionless pulley so what about the tension in the string?
 
  • #5
Check your equations... the equation for the falling mass seems to have an error of sign (directional)!
 
  • #6
drvrm said:
Check your equations... the equation for the falling mass seems to have an error of sign (directional)!
I'm sorry but could you explain? This is my first time ever introduced to any type of physics and well it's hard and this the only question I can't do.
 
  • #7
this is daily experience that strings transmit the same tension if it does not extend in length under stress ,
so the force of tension will be same.
the first equation F(tension)- force of friction = mass(A) x Acceleration
the IInd one is Force(gravity)- force(tension) = Mass(B) x Acceleration
so one knows force of friction as coefficient of friction is given. if you use the above two ,you can get the acceleration?
 
  • #8
this is daily experience that strings transmit the same tension if it does not extend in length under stress ,
so the force of tension will be same.
the first equation F(tension)- force of friction = mass(A) x Acceleration
the IInd one is Force(gravity)- force(tension) = Mass(B) x Acceleration
so one knows force of friction as coefficient of friction is given. if you use the above two ,you can get the acceleration?
 
  • #9
drvrm said:
this is daily experience that strings transmit the same tension if it does not extend in length under stress ,
so the force of tension will be same.
the first equation F(tension)- force of friction = mass(A) x Acceleration
the IInd one is Force(gravity)- force(tension) = Mass(B) x Acceleration
so one knows force of friction as coefficient of friction is given. if you use the above two ,you can get the acceleration?
Physics is hard oh god. But I guess I'll keep on trying. But from there would you just use substitution to find the acceleration?
 
  • #10
Cglez1280 said:
But from there would you just use substitution to find the acceleration?

well ,you can add or substract the simultaneous equations ,so that one of the unknown gets eliminated...this is equivalent to substitution, you have two equations so you can find two unknown.
 
  • #11
drvrm said:
well ,you can add or substract the simultaneous equations ,so that one of the unknown gets eliminated...this is equivalent to substitution, you have two equations so you can find two unknown.
Thank you so much I'm pretty sure that I got it now.
 

Related to Calculating Acceleration of M1,M2 System w/ Friction

1. How do you calculate the acceleration of an M1,M2 system with friction?

To calculate the acceleration of an M1,M2 system with friction, you will need to use Newton's Second Law of Motion. This law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. In this case, the net force would be the difference between the force of gravity and the force of friction. You can use this equation: a = (M1-M2*g)/M1 where M1 is the mass of one object, M2 is the mass of the other object, and g is the acceleration due to gravity (9.8 m/s²).

2. What are the key factors that affect the acceleration of an M1,M2 system with friction?

The key factors that affect the acceleration of an M1,M2 system with friction are the masses of the objects, the force of gravity, and the force of friction. The greater the difference in mass between the two objects, the higher the acceleration will be. The force of gravity also plays a role, as a higher force will result in a higher acceleration. Finally, the force of friction will act in the opposite direction of the net force and will decrease the overall acceleration.

3. How do you factor in the coefficient of friction when calculating acceleration?

The coefficient of friction is a value that represents the amount of resistance between two surfaces in contact. To factor it in when calculating acceleration, you will need to use this equation: a = (M1-M2*(g+μ))/M1 where μ is the coefficient of friction. This will give you a more accurate result, as it takes into account the force of friction.

4. Can the acceleration of an M1,M2 system with friction be negative?

Yes, the acceleration of an M1,M2 system with friction can be negative. This would happen if the force of friction is greater than the force of gravity, resulting in a net force in the negative direction. This negative acceleration would indicate that the objects are moving in the opposite direction of the net force and are slowing down.

5. How does the inclusion of friction affect the overall acceleration of the system?

The inclusion of friction will decrease the overall acceleration of the M1,M2 system. This is because friction creates a resistance to motion, which means that the net force acting on the objects will be lower. As a result, the acceleration will be lower compared to a system with no friction. This decrease in acceleration can also be seen in the equation, where the force of friction is subtracted from the net force.

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