1. The problem statement, all variables and given/known data http://imgur.com/WeZ2lSS If the image isn't clear, this is what it states: The speed of a particle of mass m increases at a constant rate as it moves along the path shown from location 1 to 2 and so on. The particle's speed is much less than c, the speed of light, throughout its motion. Problem: At which particle location/locations is the magnitude of the transverse component of the time rate of change of momentum ( mag. of dp / dt, perpendicular) the greatest? At which location is the magnitude of the net force acting on the particle smallest? 2. Relevant equations F = dp/dt and F = mv^2 / r (I think) 3. The attempt at a solution This question just stumped me during the exam. If the particle was speeding up at a constant rate, there was a constant force applied to it, but I do not understand how it goes tangential after a point and then makes a path with a smaller radius. Also, looking at the figure, since r was small and v was large at positions 3 and 4, I chose option E (3 and 4) for the first part since F perpendicular seemed the greatest there by mv^2/r. I also thought that since the path followed looks circular, the force experienced at 3 and 4 was the same. I do not understand how it could be circular if the speed at 4 was greater than the speed at 3. For the second part, I picked E (same at all points) since the speed was increasing at a constant rate and I figured this implied constant acceleration.