# Homework Help: Circular Motion of plane

1. Feb 22, 2005

### whatsmyname

"A fighter pilot dives his plane toward the ground at 320 m/s. He pulls out of the dive on a vertical circle. What is the minimum radius of the circle, so that the normal force on the pilot by his seat never exceeds 7G's?"

Im stuck... ive tried different things with equations like 'friction=(mass X volume^2)/radius but im not getting much of anywhere

2. Feb 22, 2005

### UrbanXrisis

$$7mg=\frac{mv^2}{r}$$
$$7rg=v^2$$
$$7r(9.8m/s^2)=(320m/s)^2$$
$$r=1492.7m$$

3. Feb 23, 2005

### whatsmyname

hrmm u just use the 7 as the friction coefficient? I didn't realize that, heh, i feel stupid now.

Ok.. yea.. i guess "g's" would be friction heh, k guess i was asleep :tongue2:

thanks tho

4. Feb 23, 2005

### UrbanXrisis

"g" is not friction. Think about it like this...when you're in a car and you're accelerating, you feel a force pushing back on you. That force is the G-force. One G is equal to your weight (mg). So, 7 g is 7mg.