An electric air conditioning unit draws 15 amps of direct current from a 94 V direct voltage source, and is used 24 hours a day during 21.1 days in July. How much will the electricity cost for the month if the local electrical rate is 10 cents/kW · hr? Answer in units of $.

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?

How do you know how many valence electrons an atom has?

Chi walked 100 meters in 5 minutes. she took another 15 minutes to walk another 400 meters to reach her house. what is her average speed?