A child in a boat throws a 5.80-kg package out horizontally with a speed of 10.0 m/s. The mass of the child is 24.6kg and the ma
1 answer:
Answer:
-0.912 m/s
Explanation:
When the package is thrown out, momentum is conserved. The total momentum after is the same as the total momentum before, which is 0, since the boat was initially at rest.
where are the mass of the child, the boat and the package, respectively.
are the velocity of the package and the boat after throwing.
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Answer:
The energy of these two photons would be the same as long as their frequencies are the same (same color, assuming that the two bulbs emit at only one wavelength.)
Explanation:
The energy of a photon is proportional to its frequency
. The constant of proportionality is Planck's Constant,
. This proportionality is known as the Planck-Einstein Relation.
.
The color of a beam of visible light depends on the frequency of the light. Assume that the two bulbs in this question each emits light of only one frequency (rather than a mix of light of different frequencies and colors.) Let and
denote the frequency of the light from each bulb.
If the color of the red light from the two bulbs is the same, those two bulbs must emit light at the same frequency: .
Thus, by the Planck-Einstein Relation, the energy of a photon from each bulb would also be the same:
.
Note that among these two bulbs, the brighter one appears brighter soley because it emits more photons per unit area in unit time. While the energy of each photon stays the same, the bulb releases more energy by emitting more of these photons.