Every element is able to be recognized individually in many different ways. A very easy and common way is using light absorption also known as spectroscopy. Every atom has electrons, and these electrons like to stay in their lowest-energy configuration. However, when photons collide with an electron it can increase it to a higher energy level.. This is absorption, and each element’s electrons absorb light at specific wavelengths related to the difference between energy levels in that atom. But the electrons want to return to their original levels, so they don’t hold onto the energy for long. When they emit the energy, they release photons with exactly the same wavelengths of light that were absorbed in the first place. An electron can release this light in any direction, so most of the light is emitted in directions away from our line of sight. Therefore, a dark line appears in the spectrum at that particular wavelength.
Because the wavelengths at which absorption lines occur are unique for each element, astronomers can measure the position of the lines to determine which elements are present in a target. The amount of light that is absorbed can also provide information about how much of each element is present.
D) because the refrigerator was much heavier than the other objects
Answer:
410.254 N
Explanation:
Force: This can be defined as the product of the mass of a body. The Unit of force is Newton (N)
Deduced from the question,
Force applied to the box to start it moving = Force of friction.
Fₐ = F
Where Fₐ = Force applied to the box to start it moving, F = Force of friction.
But,
F = μR.......................... Equation 1
Where R = normal reaction, μ = coefficient of static friction.
R = W = mg ( on a level surface)
Where m = mass of the box = 123 kg, g = acceleration due to gravity = 9.81 m/s²
R = 123×9.81
R = 1206.63 N.
Also, μ = 0.34
Substituting into equation 1
F = 1206.63×0.34
F = 410.254 N.
Thus the force applied to the box to start it moving = 410.254 N
