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
7 billion at the year of 2013
I believe that 1 millilitre of water would have a density of 1gram/cc and that is why water is used as a basis for Specific Gravity as relative to the SG of 1 of water. For example, gold has a SG of 19.2 or it is 19.2 times heavier than water.