A string is vibrating at a frequency of 440 Hz. if the frequency is doubled, what happens to the period

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?

What happens to the electrostatic force between two charged particles if the distance between them is doubled?

Unlike the idealized voltmeter, a real voltmeter has a resistance that is not infinitely large. a voltmeter with resistance rv is connected across the terminals of a battery of emf e and internal resistance r. find the potential difference vmeter measured by the voltmeter. what is vmeter?