Which of the following is true? When objects become electrically charged, 1 point it is because *
A. Both protons and electrons may be moving on to or off of the object.
B. Only protons are moving on to or off of the object.
C. Only electrons are moving on to or off of the object.
D. Becoming electrically charged has nothing to do with the movement of protons or
electrons.
E. None of the above.

Ineed with these last two questions: 1) what are two types of cold air masses that influence the weather in north america? name them and describe their humidity. 2) describe the motion of a cold air mass and a warm air mass and the weather you would expect at a warm front and an occluded front.

Wo audio speakers are placed on a vertical rail. speaker a is placed at head-level while speaker b is place at some variable height, \delta yδy, above speaker a. both speakers receive simultaneous input from a sine-wave generator so the speakers each produce a pure sinusoidal sound wave with a wavelength of 0.531 meters. calculate the lowest height that speaker b can be placed above speaker a to produce a minimum of sound heard by person standing \delta x = 7.86δx=7.86 meters directly in front of speaker a.

Using the work energy theorem. what is the velocity of a 850kg car after starting at rest when 13,000j of work is done to it.