Superman stops a "speeding locomotive" of mass 8.0x103 kg in 4.0 seconds. If the train was originally moving at 40.m/s, a) what is the change in momentum?

b.) What is the magnitude of the force which Superman exerts on the train?

A150 w lamp emits light of wavelength 590 nm uniformly in all directions. what is the photon flux (photons per unit area per unit time) on a small screen at a distance 2.3 m from the lamp? assume the photons are uniformly distributed over the surface of a sphere of radius 2.3 m.

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Which are causes of mechanical weathering? (check all that apply) a. acid rain b. plant growth c. animal actions d. carbon dioxide e. pressure release i chose b & e and got the question wrong.