Suppose a rock on earth is dropped in a vacuum and has initial speed of 0 m/s. what is the rock's speed after 2 seconds, in m/s, if it encounters no air resistance

1point) a skydiver weighing 130 lb (including equipment) falls vertically downward from an altitude of 14,000 ft and opens the parachute after 20 s of free fall. assume that the force of air resistance, which is directed opposite to the velocity, is of magnitude 0.85|v|0.85|v| when the parachute is closed and is of magnitude 17|v|17|v| when the parachute is open, where the velocity vv is measured in ft/s. assume that acceleration due to gravity has magnitude 32 ft/s/s; remember that weight is the product of mass and gravitational acceleration. find the speed of the skydiver when the parachute opens. speed is 150.6121788 ft/s find the skydiver's height when the parachute opens. height is 2338.98591 ft find the limiting velocity vlvl after the parachute opens. (think about whether this should be positive or negative.) vl=vl= 7.647 ft/s

An isotope undergoes radioactive decay by emitting radiation that has a –1 charge. what other characteristic does the radiation have?

Aboy with a mass 25 kg climbs into a small tree. he sits on a branch that is 2.o m above to the ground.what is his gravitational potential energy above the ground?