What is the frequency of microwaves with wavelength of 20-mm? (c = 3.0 x 10^8 m/s) a.15 ghz b.100 mhz c. 400 mhz d. 73 ghz

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?