Solving for Tension & Motion of 2 Masses Connected by String

[Chuck 86]

Homework Statement

Two masses of 3.40 kg and 5.50 kg are connected by a light string that passes over a frictionless pulley. Determine the tension in the string.

Calculate the acceleration of m.

Calculate the distance each mass will move in the first 1.52 seconds of motion if they start from rest

EFy=T1-m1g=may
EFy=T2-m2g=may

i have up to those equations but i don't know if I am doing this right

 

[w3390]

Your close. You need to chose an arbitrary direction in which you think the system will move. This direction for both masses will be positive. For example if you say that one mass falling will be the positive direction, the other mass rising will also be the positive direction. Therefore, one of you equations needs to be written the other way around. Instead of T2-m2g=may, what should it be using this information?

 

[Chuck 86]

So the rate of gravity for the smaller one has to be positive because it would most likley go up?

 

[rl.bhat]

Homework Statement

Two masses of 3.40 kg and 5.50 kg are connected by a light string that passes over a frictionless pulley. Determine the tension in the string.

Calculate the acceleration of m.

Calculate the distance each mass will move in the first 1.52 seconds of motion if they start from rest
/QUOTE]
You have given two masses. Which is m? Actually both will have the same acceleration.
Find the acceleration of each mass and equate them. Then solve for T. From that find the acceleration.

 

[Chuck 86]

So how do u find Y or do u just find ay together then divide by Y?

 

[rl.bhat]

When the two masses start moving from rest, heavier mass will move in the downward direction and lighter one will up.
Write down m1g - T = m1a for downward moving mass.
Similarly write down another equation for upward moving mass.
From these two equations find a and equate them, and solve for T.

 

[Chuck 86]

so then the second equation would be m2g-T=-m2a?

 

[rl.bhat]

so then the second equation would be m2g-T=-m2a?

Yes.