Why does a rubber band become warm when you stretch it repeatedly

What do you think car designers do if the damage caused by a crash test is too severe?

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.

The photo above shows oil and vinegar in a pitcher. the top make a claim about about the density of the vinegar compared to the density of the oil summarize the evidence to support the claim and explain your reasoning