When non-metric units were used in the united kingdom, a unit of mass called the pound-mass (lbm) was employed, where 1lbm=0.4539kg. (a) if there is an uncertainty of 0.0001kg in the pound-mass unit, what is its percent uncertainty? (b) based on that percent uncertainty, what mass in pound-mass has an uncertainty of 1 kg when converted to kilograms?

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.