What two quantities must stay the same in order for an object to have a constant velocity? a) the speed and kinetic energy must be constant. b) the speed and mass of the object must be constant. c) the speed and direction of travel must be constant. d) the force applied to and direction of travel must be constant.

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.