The heat of fusion of copper is 205000 J/kg. What is the mass of a copper rod that takes 4950000000 J of energy to melt the rod. Be sure to put the correct unit at the end of your answer and also for your final answer, place your final numbers two places after the decimal and round.​

An astronaut in space cannot use a scale or balance to weigh objects because there is no gravity. but she does have devices to measure distance and time accurately. she knows her own mass is 77.4 kg , but she is unsure of the mass of a large gas canister in the airless rocket. when this canister is approaching her at 3.50 m/s , she pushes against it, which slows it down to 1.30 m/s (but does not reverse it) and gives her a speed of 2.60 m/s . what is the mass of the canister?