# Homework Help: Nonuniform Circular Motion of a steel table

1. Mar 21, 2006

### pcmarine

A 600 g steel block rotates on a steel table while attached to a 1.20 m-long hollow tube. Compressed air fed through the tube and ejected from a nozzle on the back of the block exerts a thrust force of 4.30 N perpendicular to the tube. The maximum tension the tube can withstand without breaking is 60.0 N.

If the block starts from rest, how many revolutions does it make before the tube breaks?

I've done some calculations and have come up with:
Tangential Acceleration: 1.287 m/s^2
Omega: 9.13
Period: 8.513 seconds

plugged these numbers into Theta=((a)/(2*r))*(period)^2
and got 38.953 rads, or 61.19 revolutions... which was wrong

2. Mar 21, 2006

### nrqed

I am assuming that you don't mean "period", you mean the total time it takes to reach the final omega?? (it does not make sense to talk about a period since the rotation is not at a constant omega). And I am guessing that you mean 6.119 revolutions.

Can you just show how you got your tangential acceleration?

3. Mar 21, 2006

### pcmarine

Wow thanks, yeah you were right, it was actually a decimal over... 6.1 revolutions.

4. Mar 21, 2006

### nrqed

So, do you have the right answer now?

5. Mar 21, 2006

### pcmarine

yep, thanks

6. Oct 14, 2006

### Fierofiend

how the heck are you getting that time total of 8.513?

7. Oct 15, 2006

### Fierofiend

bump? Any help there?

8. Oct 15, 2006

### OlderDan

What do you think it should be?

9. Oct 15, 2006

### Fierofiend

No idea, tried for hours, couldn't come up with that answer. I figured it would be something with omega and accel, but nothing computes.

10. Oct 15, 2006

### OlderDan

Perhaps because that answer i wrong. It does have something to do with acceleration, and omega if you choose to use that. What did you try?

Last edited: Oct 15, 2006
11. Oct 15, 2006

### Fierofiend

my final velocity was 10.95 m/s and I tried to divide by my accel

12. Oct 15, 2006

### OlderDan

Let's say that is correct. What did dividing by acceleration give you? Where do you go from there?