Lee Hoeppner February 28, 2010 Astronomy 100 Homework 5 UNIT 20 RQ-2. An object slows to a halt as it rolls uphill. The kinetic energy of this object has stopped or went to zero because kinetic energy is the energy of an object in motion. It is defined as half of an objects mass times its velocity squared. The object in this case had its velocity come to a hault and its mass stayed the same, so that means that its kinetic energy also went to zero because the object is no longer in motion. UNIT 21 RQ-3. The brightness of an object is different from its luminosity. Brightness is the change in the amount of light. Brightness is equal to the total light output divided by 4 times pie times the diameter squared. Luminosity on the other hand is a measure of brightness usually denoted in Lumens. Luminosity is the amount of electromagnetic energy a body radiates per unit of time. RQ-5. A particular photon can interact with an atom if a photon hits an atom that is already excited or ready to interact. Once the interact with each other initially, the atom releases another identical photon
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