An em wave has a speed of 3 x 10 ^ 8 m/s and a wavelength of 6 x 10 ^ -7 m. what is the frequency of the wave? 90 hz 180 hz 2 x 10 ^ -15 hz 5 x 10 ^ 14 hz

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?