Most solar hot water systems are fitted with gas or electric "boosters" that can also heat the water. Describe why you think these are necessary.

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Which force is most responsible for binding together an atom's protons and neutrons? electrostatic gravitational nuclear magnetic

Truck traveling west on the highway experiences an acceleration to the east. what could be the cause of this acceleration

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?