Astudent is wearing a pair of sunglasses designed to reduce the glare from reflected surfaces. when the student tilts her head to the side and back again, she notices that the brightness of the blue sky changes in intensity. the student wonders why the intensity is affected by the orientation of her sunglasses. the light coming from the sky toward her sunglasses has most likely undergone a. absorption b. diffraction c. polarization d. refraction

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

Observations show that interstellar clouds can have almost any shape and

Why is rain likely when warm, moisture-laden air meets cold air? a) the lighter warm air will rise and cool down, causing condensation and rain. b) the cold air moves faster and pushes the warm air away, causing condensation and rain. c) the moisture in the warm air condenses on contact with the cold air, causing rain to fall. d) the cold air mixes with the warm air, reducing its temperature causing moisture to condense.