A wave has a wavelength of 125 meters is moving at a speed of 20 m/s. What is it frequency?

What pressure difference is required between the ends of a 2.0-m-long, 1.0-mm-diameter horizontal tube for 40 c water to flow through it at an average speed of 4.0 m/s?

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?

Using the free-body diagram, calculate the net force acting on the sled. is the sled in a state of dynamic equilibrium?