Ahorizontal force of 70 n is required to push a bookcase across a floor at a constant velocity. what is the net force acting on the bookcase?

Which statement is true if the refractive index of medium a is greater than that of medium b? a. total internal reflection is possible when light travels from air to medium b to medium a. b. total internal reflection is possible when light travels from medium a to medium b. c. total internal reflection is possible when light travels from medium b to medium a. d. total internal reflection is possible when light travels from air to medium a. e. total internal reflection is possible when light travels from air to medium b.

Am i correct on these two physics questions?

Thermal radiation gets its name because