During an occultation, or "covering up," of Jupiter by the Moon, an astronomer notices that it takes the Moon’s edge 90 seconds to cover Jupiter’s disk completely (starting from the moment of initial "contact"). If the Moon’s motion is assumed to be uniform and the occultation was "central" (that is, center over center), find the angular diameter of Jupiter. Express your answer in arcseconds. [Hint: Assume that Jupiter does not appear to move against the background of stars during this brief 90-second interval. You will need to convert the Moon’s angular speed from degrees per day to arcseconds 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

A100-watt light bulb illuminates a solar cell. the electricity from the solar cell operates a water pump that delivers 1 watt of power. what is the efficiency of the system?

What happens when a rubber rod is rubbed with a piece of fur?