In a marathon, how many different ways can the gold medal for first place, the silver medal for second place, and the bronze medal for third place be awarded if 20 athletes are running in the marathon?
a. 4,896
b. 7,220
c. 8,000
d. 6,840

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What term do psychologists use to designate our personal awareness of feelings, sensations, and thoughts?

Antireflective coatings on solar cells are often made by applying a thin film of silicon nitride (sinx), which has an index of refractive of 1.2, on the top of the silicon solar cell, which has a refractive index of about 3.5. however, the sun emits radiation of various wavelengths which the solar cell absorbs, and the antireflective coating can only absolutely minimize the reflection of one of these wavelengths. the coating thickness is chosen to reduce the reflection of green/yellow light (e = 2.2 ev), which is the most intense color in the solar spectrum (shown below). which of the following coatings would minimize reflection of green/yellow light? the answer is 820 nm how? what is the angular width of the central maximum of an electron traveling at 2 x 108 m/s going through a single slit of width 1 mm.

10. the kinetic theory of matter states that atomic particles will move if the temperature is above the freezing temperature of water atomic particles bounce off each other one time in their life atomic particles are constantly bumping off each other because particles are in direct contact with each other at all times all matter is made up of atomic particles which are in constant random motion