Assume that in 2010 the united states will need 2.0×1012 watts of electric power produced by thousands of 1000 mw power plants. these will almost certainly be powered by either coal or nuclear reactors. if all the energy is provided by u-235 burning reactors, how many tonnes of u-235 will be needed annually? note: rather than using the exact energy from problem 1, assume that fission of u-235 releases a "rounded" 8.e13 j/kg (assume a realistic efficiency of 45 percent for the power plant) do not enter units. if the answer is 1 million tonnes, enter 1.e6. note that a tonne is a metric ton = 1000 kg)

Explain the difference between each pair of concepts. a. frequency and relative frequency b. percentage and relative frequency a. select the correct choice below. a. frequency is the total number of observations in a data set. relative frequency is the number of times a particular distinct value occurs. b. frequency is the number of times a particular distinct value occurs. relative frequency is the ratio of the frequency of a value to the total number of observations. c. frequency is the total number of observations in a data set. relative frequency is the ratio of the number of times a particular distinct value occurs to the frequency. d. frequency is the number of times a particular distinct value occurs. relative frequency is the ratio of the frequency of two different values.

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

Aprisoner is forced to go into one of three rooms, but he can choose which room. the first room is ablaze with fire. the second one is rigged with explosives that will go off as soon as he enters. the third contains a pair of lions who haven't eaten in years. which room should he choose to survive?