A professor has to haul a cart up a ramp. The ramp has an angle of about 10 degrees and is about 5 meters long. His initial spee
d at the bottom of the ramp is 4.5 m/s, and the cart has a mass of about 80 kg. How hard does he have to push on the cart so that at the top of the ramp, its speed has not dropped below 3.6 m/s? Neglecting friction, what is the magnitude of the minimum force he has to exert on the cart?
It is usually expressed the other way: the ratio of the speed of light in a vacuum to the speed of light in a medium. In that case, it is called the "index of refraction".
A contour line connects points of the same elevation. Contour lines are usually curves. Closed contours represent hills.
Contour lines can not cross since they represent different elevations. A contour interval is the difference in elevation between one contour and an adjacent contour.
