20/45=0.4*100= 44.4 so the answer is..................................................
Answer: 44.4%
Answer:
#_photons = 30 photons / s
Explanation:
Let's start by finding the energy of a photon of light, let's use the Planck relation
E = h f
the speed of light is related to wavelength and frequency
c = λ f
we substitute
E = h c /λ
E₀ = 6.63 10⁻³⁴ 3 10⁸/500 10⁻⁹
E₀ = 3.978 10⁻¹⁹ J
now let's use a direct proportion rule. If the energy of a photon is Eo, how many fornes has an energy E = 1.2 10⁻¹⁷ J in a second
#_photons = 1 photon (E / Eo)
#_photons = 1 1.2 10⁻¹⁷ /3.978 10⁻¹⁹
#_photons = 3.0 10¹
#_photons = 30 photons / s
Displacement is B) the shortest distance between the starting point and the ending point of a motion
Explanation:
Displacement is a vector quantity; it is a vector connecting the initial position to the final position of motion of an object.
Since it is a vector, it has both a magnitude and a direction:
- The magnitude of the displacement is the length of the vector, therefore it corresponds to the shortest distance in a straight line between the starting point and the ending point of the motion
- The direction goes from the starting point to the ending point
Therefore, the correct answer is
B) the shortest distance between the starting point and the ending point of a motion
Note that displacement is very different from distance. Consider for example an object moving in a circle, returning to its initial position: in this case, the distance covered by the object is not zero (it is the length of the circle), however the displacement is zero, because the initial position corresponds to the ending position.
Learn more about distance and displacement:
brainly.com/question/3969582
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mass of the box = 20 kg
force of friction on the box due to surface



similarly kinetic friction on it



now the weight of the suspended block will be

so here the weight of the suspended block is less than the limiting friction on it
So here we will say that friction will counter balance the weight of the suspended block and it will not move at all
So acceleration of the box will be zero