"A hydraulic system is used to lift a" 51 kg "motor in a garage. If the motor sits on a piston of area" 0.25 m2, "and a force is applied to a piston of area" 84 cm2, "what is the minimum force that must be applied to lift the motor in units of N?"

How does convection affect our atmosphere? our layers of earth? our oceans?

Select for each of the following statements whether it is correct or incorrect. (a) in an isothermal expansion of an ideal gas. (b) the temperature remains constant. (b) the pressure remains constant. (c) there is work done by the gas. (d) there is heat added to the gas. (e) the change in internal energy equals zero.

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.