What is the best definition of gravity below?
a force that opposes the motion of an object.
the force 1 object exerts on another object.
speed in a given direction.
a change in velocity over time.

To practice problem-solving strategy 10.1 for energy conservation problems. a sled is being held at rest on a slope that makes an angle θ with the horizontal. after the sled is released, it slides a distance d1 down the slope and then covers the distance d2 along the horizontal terrain before stopping. find the coefficient of kinetic friction μk between the sled and the ground, assuming that it is constant throughout the trip.