# Homework Help: Newton's Laws Problem.

1. Oct 29, 2006

### AznBoi

This problem involves Newton's laws. I got the first half of the problem but I am stuck on the second part. Please take your time to guide me through it, thanks!!
Problem:
A van accelerates down a hill, going from rest to 30 m/s in 6 seconds. During the accceleration, a toy (m=.1kg) hangs by a string from the van's ceiling. The acceleration is such that the string remains perpendicular to the ceiling and to the ramp.

Determine a) the angle theta and b) the tension in the string.

Ok I found the angle theta by finding the acceleration of the van with the equation V=Vo+at. Next I found the downhill Force which is .5Newtons. Then I used F sub d(downhill force)=W sin theta. I came up with theta equals 30.677 degrees which is correct because I checked the answer.

How do I find the tension in the string? I tried using F=ma and came up with: F sub d + F sub y + (-T) = ma But that didn't work.. Fy is downward force perpendicular to the ramp, when I got x and y components.

Give me a hint for B) please! Thanks.

2. Oct 29, 2006

### tennisacerg

the only thing that i can recommend is to draw a force diagram and label all the numbers on that and see if you can figure out some sort of equation from that

3. Oct 29, 2006

### AznBoi

yeah I did.. but thats the equation I got and it doesn't work.