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What is a medium when describing the traveling of light rays and waves? 10 points
The medium is what the ray is traveling through.
The medium is the frequency that a wave travels.
The medium is the wavelength for a wave.
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Which of the

What distance does a car travel as its speed changes from 0 to 20 m/s in 17 s at constant acceleration?

How many neutrons does plutonium -196 with an atomic number of 78.

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".