# Horizontal force exerted by an engine

1. Feb 24, 2013

### theBEAST

1. The problem statement, all variables and given/known data
I am only confused about question 2.

3. The attempt at a solution
I decided to use bernoulli's equation to find velocity at point 1. With velocity at point 1 and point 2 I can use conservation of momentum to solve for the force exerted. In this case there would be Fx, pressure force at 1 and pressure force at 2. However as you can see in my second last and last lines of work, v1 comes out to be an imaginary number which is impossible.

What am I doing wrong?

2. Feb 24, 2013

### Esteban

I think, in the step where you compute the density is wrong, 'cause R's value in the international system of measures is $$R=8,314 \dfrac{J}{mol \cdot K}$$

3. Feb 25, 2013

### theBEAST

The R in this equation refers to the specific gas constant of air, so it isn't 8.3146 I believe.

4. Feb 25, 2013

### Esteban

Oh, lol ahahahha