A) One medium is air, in which light has a speed of 3.00 × 108 m/s. The other medium is ice, in which light has a speed of 2.29 × 108 m/s. Use this information to identify medium A and medium B. Explain b) Do you know in which direction the light beam is travelling? Does it matter? Explain.

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.