A train travels 80 kilometers in 2 hours, and then 79 kilometers in 4 hours. What is its average speed?

RUDIKE [14]

For number 3 the answer is solid: pizza
liquid: smoothie
gas: air diffuser

8 0

3 years ago

Determine the centroid of the shaded area shown in figure 2. Determine the moment of inertia about y-axis of the shaded area sho

Nady [450]

Answer:

centroid: (x, y) = (81.25 mm, 137.5 mm)
I = 8719.31 mm^2 for unit mass

Explanation:

Finding the desired measures requires we know a differential of area. That, in turn, requires we have a way to describe a differential of area. Here, we choose to use a vertical slice, which requires we know the area boundaries as a function of x.

The upper boundary is a line with a slope of 125/156.25 = 0.8, and a y-intercept of 125. That is, ...

y1 = 0.8x +125

The lower boundary is given in terms of y, but we can solve for y to find ...

100x = y^2

y2 = 10√x

Then our differential of area is ...

dA = (y1 -y2)dx

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The centroid is found by computing the first moment about the x- and y-axes, and dividing those values by the area of the figure.

The area will be ...

$\displaystyle A=\int_0^{156.25}{dA}=\int_0^{156.25}{(y_1-y_2)}\,dx$

The y-coordinate of the centroid is ...

$\displaystyle \overline{y}=\dfrac{S_x}{A}=\dfrac{1}{A}\int_0^{156.25}{\dfrac{y_1+y_2}{2}}\,dA=\dfrac{1}{A}\int_0^{156.25}{\dfrac{y_1+y_2}{2}(y_1-y_2)}\,dx=137.5$

Similarly, the x-coordinate is ...

$\displaystyle \overline{x}=\dfrac{S_y}{A}=\dfrac{1}{A}\int_0^{156.25}{x}\,dA=\dfrac{1}{A}\int_0^{156.25}{x(y_1-y_2)}\,dx=81.25$

That is, centroid coordinates are (x, y) = (81.25, 137.5) mm.

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The moment of inertia is the second moment of the area. If we normalize by the "mass" (area), then the integral looks a lot like the one for $\overline{x}$ , but multiplies dA by x^2 instead of x.

The attachment shows that value to be ...

I ≈ 8719.31 mm^2 (normalized by area)

The area is 16276.0416667 mm^2, if you want to "un-normalize" the moment of inertia.

7 0

3 years ago

no links never ever in the world give me a link just answer now without links What is the lithosphere? please write a full parag

nasty-shy [4]

Answer:

the solid outerpart of the earth

5 0

3 years ago

Read 2 more answers

At the start of a hockey game, the referee drops the puck between two players from opposing teams. Each player wants to push the

spin [16.1K]

Answer:

a) puck is subjected to both the forces of the hockey sticks in a horizontal direction,

b)the puck does not move since the sum of the forces is zero

c) changing the magnitude or direction of its applied force

Explanation:

a) The puck is subjected to both the forces of the hockey sticks in a horizontal direction, these forces are of equal magnitude and opposite direction since the puck is at rest.

In the direction of the y-axis (perpendicular to the ice) you have the weight of the disk and the normal to this weight that are also in equilibrium.

b) the puck does not move since the sum of the forces is zero, which implies that the forces of the hockey sticks are of equal magnitude and opposite direction.

c) the player has several ways to make the puck move

* slightly changing the angle of the club and therefore the direction of the force, in this case the disc comes out in the direction of this component

* inclined the stick slightly so that the force has a vertical component and the puck jumps in this direction

* Increasing the magnitude of the force so that the puck comes out in the opposite direction to the player

* The worst case, decreasing its force to zero and the disk comes out in its direction by the other force that had the same magnitude.

3 0

3 years ago

There are 30 students in Ms. Andrews’ fourth grade class. There are 6 times as many students in the entire fourth grade as there

KatRina [158]

Answer:

30×6=n

Explanation:

30 students in her class× 6 = number of students in the entire 4th grade.

6 0

3 years ago