Kinetic
energy is the energy that is possessed by an object that is moving. It is
calculated by one-half the product of the mass and the square of the velocity
of the object. We calculate as follows:<span>
For the truck,
KE = mv^2 / 2
KE = 20000 kg (110 km/h (1 h/3600 s)(1000 m / 1 km))^2 / 2
KE = 611111.11 J
For the astronaut,
KE = 80.0 kg (27500 km/h</span>(1 h/3600 s)(1000 m / 1 km)<span>)^2/2
KE = 611111.11 J
The kinetic energy possessed by the two bodies are the same.
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Absorption:
<span>If the wavelength of the light happens to match the distance between two electron levels in the material, it can be absorbed. Light disappears and its energy becomes part of the heat energy of the material. </span>
<span>Metals have so many free electrons that all wavelengths are absorbed -- they are opaque to xrays, visible light, radio waves, everything. </span>
<span>Pigments have specific electron gaps that absorb only the light of a specific wavelength, which we see as color </span>
<span>Transparent materials do not happen to have any gaps between electron levels that match any of the wavelengths of visible light. </span>
