# Tension of a rope problem

1. Oct 4, 2005

How much tension must a rope withstand if it is used to accelerate a 1800 kg car vertically upward at 0.60 m/s2?

could someone tell me how to start this problem? thanks so much!

2. Oct 4, 2005

### Kazza_765

Consider a free body diagram around the car. Net force = mass * accelleration. So you have the tension in the rope and gravity acting on the car, and the total of those must give you an upwards accelleration of 0.6m/s^2

3. Oct 5, 2005

i'm still confused with this problem..i thought i could just multiply 1800kg by .60 m/s^2? but i dont get the right answer...

4. Oct 5, 2005

### PhysicsinCalifornia

Is this problem neglecting air friction and mass of the rope? Also, what's pulling that rope?

Last edited: Oct 5, 2005
5. Oct 5, 2005

it doesn't say...its a webassign problem

6. Oct 5, 2005

### PhysicsinCalifornia

Ok, then what is the answer, if given? Because I got what you got too. I might be missing something

7. Oct 5, 2005

sorry...i dont have the answer either..it's due tomorrow night..hmmm...i wander why it won't work...

8. Oct 5, 2005

### PhysicsinCalifornia

You don't get the right answer even though you don't have the right answer? lol

9. Oct 5, 2005

webassign is a homework program on the internet...it tells you right away if you're wrong or right...but doesn't give you the right answer until after its due or if you get the answer right.

10. Oct 5, 2005

### cscott

I think what Kazza is saying is $\vec{F_T} - mg = m\vec{a}$. If that's correct then you can think of a free body diagram of the rope with the upward force equal to ma, and the downward force equal to mg. But don't take my word on it

Last edited: Oct 5, 2005
11. Oct 5, 2005