A bucket is filled to the brim with water and hanging on a spring scale. A heavy toy boat is placed in the water and water pours over the edge of the bucket while the boat remains floating in the bucket. Does the overall reading on the spring scale go up, down, or does it remain the same

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?