On a keyboard, you strike the lowest note, a very low A, whose frequency is 27.5 Hz. What is the period of one vibration of this tone? As the sound leaves the instrument at a speed of 340 m/s what is its wavelength in air

An observer that stands still as the electron moves by him, will observe

Unpolarized light falls on two polarizer sheets whose transmission axes are at right angles. a third polarizer is placed between the first two so that its axis makes a 52-degree angle with the axis of the first polarizer. a) what fraction of the incident light intensity is transmitted through the first polaroid? b) what fraction of the incident light intensity is transmitted through the second polaroid? c) what is the angle of polarization of the light that enters the third polaroid? d) what fraction of the incident light intensity is transmitted through the third polaroid. e) what happens if the middle polaroid is removed?

If the ama of the inclined plane below is 2, calculate the ima and efficiency. ima = efficiency =