An electron starts with a speed of 5.50×105 m/s . It moves in a region with an electric field. Some time later the electron has been brought to res What is the change in electric potential V in going from the initial to the final position? Make sure your sign is correct. Express your answer with the appropriate units.

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?