A roller-coaster car has a potential energy of
619 J and a kinetic energy of 156 J at point A
in its travel. At the low point of the ride, the
potential energy is zero, and 56 J of work has
been done against friction since it left point
A. What is the kinetic energy of the roller
coaster at this low point?
Answer in units of J. Your answer must be
within ± 3.0%