Energy is calculated as power*time, so give the wattage of 1200 W (equivalent to 1200 Joules/second) and time of 30 seconds, multiplying these gives 36000 J or 36 kJ of electrical energy.
If electrical charge or current is needed: Power = voltage * current, so given the power of 1200 watts and voltage of 120 V, current is 1200 W / 120 V = 10 Amperes. Charge is calculated by multiplying 10 A*30 s = 300 C.
To solve this problem it is necessary to apply the concepts related to the change of Energy in photons and the conservation of energy.
From the theory we could consider that the energy change is subject to

Where
Initial Energy
Energy loses
Replacing we have that


Therefore the Kinetic energy of the electron once it has broken free of the metal surface is 0.8eV
Answer: C
Explanation:
A collision in which the objects stick together is sometimes called “perfectly inelastic“
Answer:
Last option in the list of possible answers, with U235 and n (neutron) in the left (originators) of the reaction diagram.
Explanation:
Uranium 235 (which is a fissile isotope of uranium) plus slow neutrons is what produce the chain reaction that feeds nuclear reactors.