Who discovered that the atom is mostly empty space

What are the theoretical properties of a gas at a temperature of 0 kelvin?

Awave is produced in a rope. the wave has a speed of 33 m/s and a frequency of 22 hz.

The position of a crate sliding down a ramp is given by x=(0.05t^3) m, y=(1.7t^2) m, z=(6−0.85t^5/2) m, where t is in seconds. (a) determine the magnitude of the crate's velocity when t = 2 s. (b) determine the magnitude of the crate's acceleration when t = 2 s.