A0.100 kg ball hangs from a spring of negligible mass. when the ball is hung on the spring and is at rest, the spring is stretched by 0.200 m from its equilibrium to a new equilibrium, in which the tension in the spring balances the weight of the ball. what is the spring constant of this spring

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?