3) If light that normally travels at 299,000,000m/s only travels at 200671141 m/s through a material. What is the material most likely made out of? (use the table)
Indexes of Refraction
Air: 1.00
Barium Glass: 1.60
Water 1.33 Crown Glass: 1.52
CR39: 1.50 Polycarbonate: 1.59
Diamond: 2.45 Flint Glass: 1.70

Asled is being held at rest on a slope that makes an angle θ with the horizontal. after the sled is released, it slidesa distance d1 down the slope and then covers the distance d2 alongthe horizontal terrain before stopping. find the coefficient ofkinetic friction μk between the sled and the ground, assumingthat it is constant throughout the trip. find the coefficient of kinetic frictionμk. express your answer in terms of someor all of the variables d1, d2, and θ.