# Final speed of a rotating spaceship!

1. Mar 15, 2010

### Susanne217

1. The problem statement, all variables and given/known data

Lets imagine that in the movie 2010. The Discovery is rotating then they find it. Every time the ship reaches a speed in the circular motion of 24000 km/h the engine gives a burst of energy. Which amounts to 20 kN. The mass of the Discovery is 30.000 kg. The time from the engine gives a burst amounted to the above size to the ships engine going to sleep is 3 minutes.
How do I calculate the extra speed v_final which is achieved by the engine burst after the three minutes. Necletecting all other forces?

Is there a specific formula?

According to my book. the answer is suppsed to be 24400 km/h.

I have to tried to the formula

$$F = 1/2 \cdot m v_f^2 - 1/2 \cdot m v_i^2$$

But using that formula I arrive at v_final = v_initial.

What am I doing wrong?

Sincerely
Susanne

2. Mar 15, 2010

### Filip Larsen

Your scenario has the information: acceleration force (20 kN), mass (30 ton) and time (180 seconds); and you want to calculate the resulting change of speed. A way forward could be to figure out how force and mass relates to acceleration and how (constant) acceleration relates to change in speed.