Suppose that scientists observe violent gas eruptions on a planet with an acceleration due to gravity of 3.8 m/s2. The jets throw sand and dust about 75 m above the surface. What is the speed i of the material just as it leaves the surface?
Scientists estimate that the jets originate as high‑pressure gas speeds through vents just below ground at about 160 km/h. How much energy per kilogram of material does the jet lose to non conservative forces as the high‑speed matter forces its way to the surface and into the air?

Air is held within a frictionless piston-cylinder container, which is oriented vertically. the mass of the piston is 0.45 kg and the cross-sectional area is 0.0030 m2. initially (state 1) the pressure of the gas is sufficient to support the weight of the piston as well as the force exerted by the atmospheric pressure ( 101.32 kpa). the volume occupied by the air within the cylinder in state 1 is 1.00 liter. one end of a spring (with spring constant k = 1000 n/m) is attached to the top of the piston, while the other end of the spring is attached to a stage that can move vertically. initially the spring is undeflected and therefore exerts no force. then the stage is then moved quasistatically downward a distance of 10.0 cm, at which point the system reaches state 2. the piston-cylinder is not insulated; rather it remains in diathermal contact with the surroundings, which are at a constant temperature of 300 k. what is the change of pressure within the container?

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?

(a) if the pressure in gas is doubled while its volume is held constant, by what factor do (i) vrms and (ii) change? (b) is it possible to boil water at room temperature (20oc) without heating it? explain.