An elevator descends into a mine shaft at rate of 15 metre per minute. a) What will be its position after 1 hour?
b) If it begins to descend 25m above ground, what will be its position after 45 minutes?

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.