Tension between 2 blocks and friction.


by CaptainSFS
Tags: blocks, friction, tension
CaptainSFS
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#1
Sep21-08, 08:18 PM
P: 58
1. The problem statement, all variables and given/known data



A block of mass m1 = 2 kg and a block of mass m2 = 3 kg are tied together and are pulled from rest across the floor by a force of P = 25 N. The coefficient of friction of the blocks with the floor is = 0.14.

I found the acceleration to be 3.6266 m/s2.

I need to find the tension in the string between the blocks.

2. Relevant equations

F=ma and Ff=u(mg)

3. The attempt at a solution

The total frictional force is 6.867 N. m1 has a frictional force of 2.7468 i think, and m2 has a frictional force of 6.7596 i think. I think the pulling force on m1 is 7.2532 N. I mean, i tried creating different summations of the forces, but I don't know what I'm doing wrong. I'm sure I could figure it out, but I need to at least know how to add the forces up in each direction. Thanks so much.
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PhanthomJay
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#2
Sep22-08, 10:59 AM
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Quote Quote by CaptainSFS View Post
1. The problem statement, all variables and given/known data



A block of mass m1 = 2 kg and a block of mass m2 = 3 kg are tied together and are pulled from rest across the floor by a force of P = 25 N. The coefficient of friction of the blocks with the floor is = 0.14.

I found the acceleration to be 3.6266 m/s2.
Good. You should round it off though to 3.6

The total frictional force is 6.867 N.
yes
m1 has a frictional force of 2.7468 i think,
yes
and m2 has a frictional force of 6.7596 i think.
where did you get this?
I think the pulling force on m1 is 7.2532 N.
how did you arrive at this?
I mean, i tried creating different summations of the forces, but I don't know what I'm doing wrong.
Draw a Free Body Diagram of block 1 (isolate it) , and examine the forces acting on it to solve for T using Newton 2. What is the acceleration of block 1?
CaptainSFS
CaptainSFS is offline
#3
Sep22-08, 08:50 PM
P: 58
okay, I typed the wrong number in for m2's frictional force. I meant to type in 4.1202 N. I arrived at m1's pulling force by (2)(3.6) = F. Right, I thought I tried creating a FBD but for some reason I'm doing something wrong. Is the acceleration on block m1 = 2.25 m/s2? At this point I am not sure what I am supposed to do.

EDIT: wait, doesn't the acceleration have to be equal to 3.6m/s2?

CaptainSFS
CaptainSFS is offline
#4
Sep22-08, 11:27 PM
P: 58

Tension between 2 blocks and friction.


Hey, if someone could help me. I'm really stuck on this one, I just think I've dug myself a deeper hole trying to work this out. I would really appreciate any more help.

EDIT: I solved it. it's 10 N...


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