The ability to pick up small objects, to stack objects, and to carry objects appears first during which time period?
2 answers:
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Answer:
4500 J
Explanation:
First, let's define some equations and derivations.
Our potential energy formula is:
Where <em>m </em>is mass (in kg), <em>g</em> is the gravitational constant (in m/s²), and <em>h</em> is height (in m).
We also know that <em>mg</em> is equal to the weight of an object (in N), from Newton's 2nd Law of Motion: F = ma (Force is equal to [constant] mass times acceleration).
Therefore, we can simply substitute force into the equation:
Where <em>F</em> is the force (in N) and <em>h</em> is still height (in m).
Now we can calculate the amount of potential energy in our system, measured in joules.
Substitute in the given variables, F = 500 N and h = 9 m:
Using simple Pre-Algebra rules, we find that:
This tells us that the we have 4500 joules of potential energy when I am 9 meters above the water on the edge of the diving board.
Answer:
B. Maximum velocity of ejected electrons.
Explanation:
The ejection of electrons form a metal surface when the metal surface is exposed to a monochromatic electromagnetic wave of sufficiently short wavelength or higher frequency (or equivalently, above a threshold frequency), which leads to the enough energy of the wave to incident and get absorbed to the exposed surface emits electrons. This phenomenon is known as the photoelectric effect or photo-emission.
The minimum amount of energy required by a metal surface to eject an electron from its surface is called work function of metal surface.
The electrons thus emitted are called photo-electrons.
The current produced as a result is called photo electricity.
Energy of photon is given by:
where:
h = Planck's constant
frequency of the incident radiation.