Agirl turns over a plastic cup so that the open end is facing down, and then
completely submerges it in a pool of water. in doing so, she traps air in the
cup so that both the air and the cup have a volume of 1185 cm?
approximately how much force must she use to keep the cup from popping
up out of the water, assuming that the weight of the cup and air can be
neglected? (recall that the density of water is 0.001 kg/cm and g = 9.81
m/s2.)

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.