Aperson struggles very hard to lift a large boulder. he puts in so much effort, he starts to sweat, his heart rate increases, and he gets really tired. all of his effort is for nothing, the boulder does not move at all. in this situation, has work been done? explain! *use the scientific definition of "work" to answer this question.

Is it possible to use the energy from two atoms colliding to create a clean burning lasting fuel source with a large amount of force? is it also possible to harness that energy from the two atoms colliding to create a clean energy source that will last for years from just two atoms colliding. is there a possibility to control and store that energy for years but slowly let the energy out enough to power cities cheaper and faster.

Abird flies directly overhead from where you stand at an altitude of 300.0 m and at a speed horizontal to the ground of 20.0 m/s. the bird has a mass of 2.0 kg. the radius vector to the bird makes an angle \thetaθ with respect to the ground. the radius vector to the bird and its momentum vector lie in the xyxy-plane. what is the bird’s angular momentum about the point where you are standing?

At what time would the magnitude of the velocity reach 36.00 km/hr