A person can jump out of an airplane at 5000 feet, without a parachute, AND land on the ground safely (without any injury), IF they can manage to do what physics trick? Lengthen the moment/time of impact
Bend knees right before impact
Spread out arms and legs to slow down
Shorten the length/time of impact

If a simple machine reduces the strength of a force, what must be increased?

Debris produced by mining is called

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.