Assume that the average galaxy contains 1011 msun and that the average distance between galaxies is 10 million light-years. calculate the average density of matter (mass per unit volume) in galaxies. what fraction is this of the critical density we calculated in the chapter?

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

What do we mean by the event horizon of a black hole?

Compare the maximum rate of heat transfer to the basal metabolic rate by converting a bmr of 88 kcal/hr into watts. what is the value? from this comparison you should see why the body can accommodate a modes amount of activity in hot weather but strenuous activity would increase the metabolic rate above the body's ability to remove heat [12].