Why is it impossible for a heat engine to be 100% efficient? A. Some heat is always lost to the environment.

B. Entropy always decreases in a heat engine.

C. Work cannot be done on a heat engine.

D. Heat is constantly being created.

Apiano tuner uses a tuner to create a tone of 5.00 x 10² hz. when a key on the piano is struck he hears 5 beats per second. what is a possible frequency of vibration for the piano string? 2500 hz 1300 hz 605 hz 495 hz

Gordon is going for a run through the park, but it is cold outside. the low outside temperature could affect his personal safety.

Ultraviolet radiation is dangerous because it has a high enough energy to damage skin cells. what is the best explanation of the relationship between wavelength and wave energy? a) wave energy is related only to frequency, not wavelength. b) longer wavelengths have lower frequencies but higher energy. c) the shorter the wavelength, the lower the frequency and the higher the energy. d) the shorter the wavelength, the higher the frequency and the higher the energy.