A forensic investigator notes that an 8g lead bullet melted completely upon impact with a doorframe. Assuming the bullet was fired at room temperature (~20 C), what would be the minimum muzzle velocity of the gun (in other words, how fast was the bullet traveling)?

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?