# Normal tangential co-ordinates(ut,un)

1. Mar 3, 2014

### princejan7

1. The problem statement, all variables and given/known data
A jet is coming out of a dive and a sensor in the pilots seat measures a force of 800lb for a pilot whose weight is 180lb. If the jet's instruments indicate that the plane is travelling at 850mph, determine the radius of curvature, p, of the plane's path at this instant

2. Relevant equations

a= (dv/dt)at + ((v^2)/p)an

3. The attempt at a solution

So I think this involves the component of acceleration in the direction perpendicular to the
flights path at that point?

so an=(v^2)/p

But I don't know what an is at that point?

Also, for what kind of problems should the polar coordinate system be used over the normal-tangential co-ordinate system?

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

http://postimg.org/image/45lhhjrqp/

2. Relevant equations

same as above question

3. The attempt at a solution

So at B, I think I can find the component of acceleration perpendicular to the path(which will point towards the center in this case?) using (v^2)/p and then use that to find the resultant force in the same direction using RFn=m(an)
But I don't know what to do next. Is that enough information to solve simultaneously for both the unknown forces?

2. Mar 3, 2014

### Staff: Mentor

The pilot's seat exerts a force on him to (i) exactly balance his weight, and (ii) to force him to follow a circular path. At the bottom of the plane's loop, what is the direction in which each of these forces acts?