Question

The good Professor is driving to a professional meeting in Boulder and decided to take along a few of her students. Going 70 mph down US 287 Angelo rounded a fairly tight curve near the train tracks. She was turning to the right and the car followed the road. During this curve one student sitting shotgun on the passenger side felt a strong push up against the passenger door until the good Professor has the car going straight. The professor, never missing a chance to teach asked "is that force real or not". Naturally I.M.Smart responded yes, and I can prove it. The Prof says no, and she can prove it. Who is right and WHY.

Answer 1

Whether the 'fictitious' force is actually fictiotious or not depends on the frame of reference of the observer.

A real force is one that is applied externally, thus, from a moving frame of reference, this is an external force and hence from the car's (non inertial frame) frame, student I.M.Smart is right. But from the ground's frame, the acceleration is only due to the car and hence, since the student's initial velocity is in one direction, its tendency is to stay in that direction until the car 's acceleration changes the student's velocity (in terms of direction). Hence, the professor is right when the phenomenon is observed from an inertial or a stationary frame of reference.