# Newtons Laws, Finding tension in the tow cable and foce

1. Oct 15, 2013

### mjm3

1. The problem statement, all variables and given/known data
Just started tension problems and having some trouble figuring out how to approach the problem. Thanks for any help in advance.

Consider a rocket that is taking off and towing a large container of trash. The
rocket’s engines exert a force, F, that causes the rocket and container to accelerate at
4.50 m/s2. The rocket has a mass of 3.00 × 103 kg, and the container has a mass of
1.00 × 103 kg. Find the tension in the tow cable and the force, F.

2. Relevant equations

3. The attempt at a solution

2. Oct 15, 2013

### Enigman

3. Oct 15, 2013

### mjm3

mass a of the rocket. FN upward is the F(RA), downward we have m(ag) and also m(bg)?
mass b of container. Upward would be F(t) and FN would be F(RB)? downward m(bg).

I have the most trouble the free body diagrams.

Work. Part 1, A= F / ma+mb. F=A(ma+mb) = 1.80x10^4 N
Part 2, Ft=mb * a = 4.50x10^3 N

4. Oct 15, 2013

### Enigman

What is FN?
Seems good.

5. Oct 15, 2013

### mjm3

Sorry I was meaning to write it as the Normal Force, NF better?

6. Oct 15, 2013

### Enigman

I was afraid so...there is no normal force here! Normal forces come in play when there is a body in contact with another. See: http://en.wikipedia.org/wiki/Normal_force
For normal force it is general practice to write Fn or just N.

7. Oct 15, 2013

### mjm3

Thanks for the help. Just clarifying Fn made this system much easier to understand.