Why can humans float in space but not on Earth?

Apiano tuner uses a tuner to create a tone of 5.00 x 10² hz. when a key on the piano is struck he hears 5 beats per second. what is a possible frequency of vibration for the piano string? 2500 hz 1300 hz 605 hz 495 hz

Iwill give brainliest if you answer right : )

Suppose you increase your walking speed from 7 m/s to 13 m/s in a period of 2 s. what is your acceleration?