One of the waste products of a nuclear reactor is plutonium–239 (239pu). this nucleus is radioactive and decays by splitting into a helium-4 nucleus and a uranium-235 nucleus (4he + 235u), the latter of which is also radioactive and will itself decay some time later. the energy emitted in the plutonium decay is 8.40 ✕ 10^−13 j and is entirely converted to kinetic energy of the helium and uranium nuclei. the mass of the helium nucleus is 6.68 ✕ 10^−27 kg, while that of the uranium is 3.92 ✕ 10^−25 kg (note that the ratio of the masses is 4 to 235).
a. calculate the velocities of the two nuclei, assuming the plutonium nucleus is originally at rest. (enter the magnitude of the velocities in m/s.)
b. how much kinetic energy in joules does each nucleus carry away? note that the data given here are accurate to three digits only.

4.at 0 ºc, some amount of energy is required to change 1 kg of water from a solid into a liquid. if you had a 2 kg piece of ice, what effect would this have on the amount of thermal energy required to change the water from a solid to a liquid? it would require more energy to change solid water into liquid water because there are more molecules in this larger piece of ice. it would still require the same amount of energy to change solid water into liquid water because the entire piece of ice would still gain the same amount of energy in each case. it would require energy to be removed from the 2 kg piece of ice. the larger piece of ice already has more total energy than the smaller piece of ice, so energy must be removed for the ice to become liquid. it would require less energy to change solid water into liquid water because the energy would spread through the ice more quickly and the ice already has a larger total amount of energy because it is larger than a 1 kg piece of ice.