# Tension Q

1. Oct 13, 2005

### SS2006

theres two blocks

a 4 KG one and a 5 KG one right next to each other, connected by a c ord, the 5 KG is on the right and its conected to another cord pulling 30 N to the right.

so

Box1----Box2----30 N
get it
so theyre asking for the tension in the cord connecting them
it slipped my mind how to do this :(
i got acceleration of the system to be 3.3 m/s tho

2. Oct 13, 2005

### Pyrrhus

Did you draw the FBDs?

3. Oct 13, 2005

### SS2006

yes i did
but im confused really
i know its a simple questoin
test is 2morrow

4. Oct 13, 2005

### Pyrrhus

Ok then let me see your equations for each body

5. Oct 13, 2005

### SS2006

well for acceleration

i did

9a = 30
and got 3.33 m/s, which was right
now they ask for tension of cord connecting them, i just hit a blank spot here for some reason.
lets say i make a fbd for the 5 kg box, so it got 30 N going one way, and the other way? is it 4 x10? no right. and theres no friction btw
i cant think, relaly, just help me out, im not trying to get u guyst od o my hw or antyhign honeslty, this is jsut a review Q for a test tmorrow!

6. Oct 13, 2005

### hotvette

Explain how you got a. Also, consider the following:

1. What force is acting on the left block?
2. What can you say about the relationship between the acceleration of block 1 and the acceleration of block 2
3. What equations of motion are you using?

7. Oct 13, 2005

### Pyrrhus

Basicly you considered your system the whole 2 boxes, that's ok, but then the tension force will be an internal force instead of an external force, analyze for each body in order to find the tension.

8. Oct 13, 2005

### SS2006

k got the asnwer
sorry for the stupidness
i had some brain crmap or something :D

9. Oct 16, 2005

### Alpha2005

Further thought to the above question by SS2006, can I know how come everytime we draw a FBD, the rope has force in both opposite direction

box 1 -- box 2---
for the -- between the box1 and 2, the direction of force is box1--<-->--box2--30N
*the arrow shown is for the tension of the rope only
hope you get what I mean:)

Last edited: Oct 16, 2005
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