Answer:
v = 16.23 m/s²
Explanation:
In the problems that have friction force this must be included in the energy conservation equation, in these cases the friction force performs dissipative work that is equal to the decrease in mechanical energy
= -
Let's look for the initial mechanical energy
= Ke = ½ k x²
Final energy
= K + U = ½ m v² + mg y
The work of the rubbing force is
= - fr d.
Let's look for the missing terms, let's start with the amount the spring compresses, let's use Hooke's law
F = - k x
x = F / k
x = 4400/1100
x = 4 m
Let's write the equation and calculate
-Fr d = (1/2 m v² + ½ mg y) - ½ k x²
½ m v² = -fr .d + 1 / 2k x² - ½ m g y
v² = 2/m (- fr .d + 1/2 k x² - ½ m g y)
v² = 2/60 (-40 4 + ½ 1100 4² - ½ 60 9.8 2.5)
v = √(7905/ 30)
v = 16.23 m/s²
Force is ALWAYS measured in Newtons (N)
The answer is the third choice, "the brightness of the beam of light increases"
According to Einstein’s theory, an increase in the number of photons (per unit are) affects a beam of light by causing a higher intensity. <span> Sometimes, the term "brightness" is used when referring to the </span>intensity<span> of a color, a</span><span>lthough there are instances where this can be a misleading term when we try to describe </span><span>intensity</span>