The image formed by a concave mirror is located -11.30 cm behind the mirror when an object is 3.70 cm in front of the mirror. What is the focal length of the mirror?

When an object is heated it contracts. a. true b. false

The force needed to overcome static friction is usually less than that needed to overcome kinetic friction.true or false?

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.