One watt (w) is equal to 1 j/s. assuming that 5.0% of the energy output of a 75 w light bulb is visible light and that the average wavelength of the visible light is 550 nm, how many photons are emitted by the light bulb per second?

Under conditions for which the same room temperature is maintained by a heating or cooling system, it is not uncommon for a person to feel chilled in the winter but comfortable in the summer. provide a plausible explanation for this situation (with supporting calculations) by considering a room whose air temperature is maintained at 20â°c throughout the year, while the walls of the room are nominally at 27â°c and 14â°c in the summer and winter, respectively. the exposed surface of a person in the room may be assumed to be at a temperature of 32â°c throughout the year and to have an emissivity of 0.90. the coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 w/m2 â‹…â‹… k. what is the ratio of the thermal resistance due to convection to the thermal resistance due to radiation in the summer? what is the ratio of thermal resistances in the winter

Aplane travels 1000 miles in 5 hours .what is the planes average speed?

Acompound machine is also called a machine. a. force b. simple c. complex d. directional