Identify the topic sentence in the given paragraph. Humans need sleep to help their bralns function properly. The brain needs a minimum number of hours to rest and organize itself. The number of hours depends on age. For example, babies need an average of 14 to 16 hours of rest daily, while adults can function on about 6 to 8 hours. Scientists are not completely sure what the brain does during sleep periods, but they do know that the brain sorts and stores information and replaces chemicals when a person sleeps.

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Modify the equation fδt=δ (mv) to find the force of friction.

A0.580-kg rock is tied to the end of a string and is swung in a circle with a radius of 0.500 meters. the velocity of the rock is 4.50 m/s. what is the centripetal force acting on the rock? 15.5 n 5.22 n 69.8 n 23.5 n

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.