Polaroid sunglasses help when skiing on snow on a sunny day by reducing the sunlight from the snow. This light from the snow has been polarized by:
a. optical activity.
c. reflection.
b. selective absorption.
d. double refraction.
C
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Calorimetry: Two experimental runs are performed to determine the calorimetric properties of an alcohol which has a melting point of -10°C. In the first run, a 200-g cube of frozen alcohol, at the melting point, is added to 300 g of water at 20°C in a styrofoam container. When thermal equilibrium is reached, the alcohol-water solution is at a temperature of 5°C. In the second run, an identical cube of alcohol is added to 500 g of water at 20°C and the temperature at thermal equilibrium is 10°C. The specific heat capacity of water is 4190 J/kg ? K. Assume no heat is exchanged with the styrofoam container and the surroundings. What is the specific heat capacity of the alcohol?
A. 1700 J/kg ? K B. 1900 J/kg ? K C. 2100 J/kg ? K D. 2300 J/kg ? K E. 2500 J/kg ? K
In the hydrogen atom the potential energy is negative, but the absolute value of the potential energy
a. is equal to the kinetic energy of the electron. b. is twice the kinetic energy of the electron. c. is half the kinetic energy of the electron. d. is equal to n2 times the kinetic energy of the electron.
A 2.0-kg block sliding on a frictionless horizontal surface is attached to one end of a horizontal spring (k = 600 N/m) which has its other end fixed. The speed of the block when the spring is extended 20 cm is equal to 3.0 m/s. What is the maximum speed of this block as it oscillates?
a. 4.6 m/s b. 5.3 m/s c. 5.7 m/s d. 4.9 m/s e. 3.5 m/s
Acceleration is greater for a satellite when it is at the
A) apogee (farthest point). B) perigee (closest point). C) zenith. D) same acceleration at all of the above places.