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Question # 2
Answer explained by: DinoP
Here is a 3D representation of what is wanted from this question.
Volume is defined by the function f(x) = l * w * h, where:
(w) width = 1 cm
(h) height = *As height is dependent on x*
(l) length = x2 x1
Density is defined by the function g(x) = x2
x2 = is the average density of the piece of metal.
Mass = (Volume)(Density)
Volume = f(x) =
Density = g(x) =
Mass = f(x) * g(x)
Mass =
Using the Left Hand Riemann sum we recieve:
Now evaluating the Riemann Sum from x=0 to x=4 we get:
+
x2x1 is the interval in which the rectangle expands to which in this case is 1 for 4 equal subdivisions.
+
+
(0) + (1/2) + (4/3) +(9/4)ggg g
(1/2)*6 + (4/3)*6 +(9/4)*6Multiply by 6 to make a common denomenator, so it is easier to add the fractions together.
(6/12) + (16/12) +(27/12)
49/12 Is the numerical value for mass of the piece of metal when using the Rieman sum.
ggg
g
g g g
Some changes must be made to the equation of mass of the piece of metal so the definite integral theorem can be used.
Mass =
Newly created Mass formula:
The value of x2x1 is now converted into x, because we are not looking for a piece of the length, we are looking for the whole length.
Mass = dx
Mass = dx
Mass =
a & b are inverted because the graph is monotone decreasing, 0 is larger than 4, so a & b must be inverted.
Mass = 0
4
Mass =
Mass = The total mass of the metal object is 64/5 grams which is equivalent to 12.8 grams.
g
g
Question #2 Completely Explained