A physics professor uses an air-track cart of mass m to compress a spring of constant k by an amount x from its equilibrium length. The air-track has negligible friction. When she lets go, the spring launches the cart. What cart velocity should she expect after it is launched by the spring

The two most prominent wavelengths in the light emitted by a hydrogen discharge lamp are 656 nm(red) and 486 nm (blue). light from a hydrogen lamp illuminates a diffraction grating with 520lines/mm , and the light is observed on a screen 1.5m behind the grating. part a what is the distance between the first-order red and blue fringes? express your answer to two significant figures and include the appropriate units.

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

Assume that a person skiing high in the mountains at an altitude of h = 15100 ft takes in the same volume of air with each breath as she does while walking at sea level. determine the ratio of the mass of oxygen inhaled for each breath at this high altitude compared to that at sea level. assume that the air composition (i.e. % of air that is oxygen) is the same at sea level as it is at 15100 ft.