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3 years ago

6 questions:

1 answer:

5 0

For question 1: What percentage of the earth is covered by water?

Your answer for question 1: About 71 percent of the earth's surface is covered by water.

For Question 2: Did dinosaurs and humans ever exist at the same time?

Your answer for question 2: No. Dinosaurs went extinct at the end of the Cretaceous period, 65 million years ago. Modern humans did not appear until around 200,000 years ago.

For question 3: What is Darwin's theory of the origin of species?

Your answer for question 3: Darwin's theory of species origination says that natural selection chooses organisms that possess variable and heritable traits and that are best suited for their environments.

For question 4: Why is the sky blue?

Your answer for question 4:
 Solar radiation sunlight is scattered across the atmosphere by a process called diffused sky radiation. The sky is blue because much more short-wave radiation, blue light, is scattered across the sky than long-wave radiation, red light.

For question 5: What causes a rainbow?

Your answer for question 5: Rainbows can be seen when there are water droplets in the air and the sun is shining. Sunlight, which contains all colors, is refracted, or bent, off the droplets at different angles, splitting into its different colors of red, orange, yellow, green, blue, indigo and violet.

For question 6: Why does a year consist of 365 days and a day of 24 hours?

Your answer for question 6: A year, 365 days, is the time it takes for the Earth to travel around the Sun. A day, 24 hours, is the time it takes for the Earth to spin around once on its axis.

Hope all of this helps you today

You might be interested in

When a person floating in swimming pool, they experience an upthrust. what causes this effect?

velikii [3]

When your head sticks out of the water the upthrust reduces as your head is no longer displacing water, and there is 0 resultant force so you float at that level. hope this helps, can i get brainliest please

6 0

4 years ago

What are dimensionless quantities??

bearhunter [10]

Answer:

Characteristic numbers are dimensionless numbers used in fluid dynamics to describe a character of the flow. To compare a real situation with a small-scale model it is necessary to keep the important characteristic numbers the same. Names of these numbers were standardized in ISO 31, part 12.

Explanation:

7 0

3 years ago

A thin uniform rod of mass M and length L is bent at its center so that the two segments are now perpendicular to each other. Fi

Tatiana [17]

Answer:

(a) I_A=1/12ML²

(b) I_B=1/3ML²

Explanation:

We know that the moment of inertia of a rod of mass M and lenght L about its center is 1/12ML².

(a) If the rod is bent exactly at its center, the distance from every point of the rod to the axis doesn't change. Since the moment of inertia depends on the distance of every mass to this axis, the moment of inertia remains the same. In other words, I_A=1/12ML².

(b) The two ends and the point where the two segments meet form an isorrectangle triangle. So the distance between the ends d can be calculated using the Pythagorean Theorem:

$d=\sqrt{(\frac{1}{2}L) ^{2}+(\frac{1}{2}L) ^{2} } =\sqrt{\frac{1}{2}L^{2} } =\frac{1}{\sqrt{2} } L=\frac{\sqrt{2} }{2} L$

Next, the point where the two segments meet, the midpoint of the line connecting the two ends of the rod, and an end of the rod form another rectangle triangle, so we can calculate the distance between the two axis x using Pythagorean Theorem again:

$x=\sqrt{(\frac{1}{2}L)^{2}-(\frac{\sqrt{2}}{4}L) ^{2} } =\sqrt{\frac{1}{8} L^{2} } =\frac{1}{2\sqrt{2}} L=\frac{\sqrt{2}}{4} L$

Finally, using the Parallel Axis Theorem, we calculate I_B:

$I_B=I_A+Mx^{2} \\\\I_B=\frac{1}{12} ML^{2} +\frac{1}{4} ML^{2} =\frac{1}{3} ML^{2}$

5 0

3 years ago

A certain lightbulb has a tungsten filament with a resistance of 26 Ω when cold and 170 Ω when hot. If the equation R = R0 [1 +

iris [78.8K]

Answer:

Explanation: The equation that relates resistance of tungsten at different temperatures is as follows

R = R₀ [1 + α ∆T] , R₀ is resistance at lower temperature , R is resistance at higher temperature . α is temperature coefficient of resistivity and ∆T is rise in temperature .

Putting the values

170 = 26 [1 + .0045 ∆T]

∆T = 1230.75

lower temperature = 40◦C

higher temperature = 1230 + 40

= 1270◦C

5 0

3 years ago

What tension would you need to make a middle c (261.6 hz) fundamental mode on a 1 m string (for example, on a harp)? the linear

Allisa [31]

The frequency of middle C on a string is
f = 261.6 Hz.

The given linear density is
ρ = 0.02 g/cm = (0.02 x 10⁻³ kg)/(10⁻² m)
= 0.002 kg/m

The length of the string is L = 1 m.

Let T = the tension in the string (N).
The velocity of the standing wave is
$v= \sqrt{ \frac{T}{\rho} }$

In the fundamental mode, the wavelength, λ, is equal to the length, L.
That is
Because v = fλ, therefore
$\sqrt{ \frac{T}{\rho} } =f \lambda = fL \\\\ \frac{T}{\rho} = (fL)^{2} \\\\ T = \rho (fL)^{2}$

From given information, obtain
T = (0.002 kg/m)*(261.6 1/s)²*(1 m)²
= 136.87 N

Answer: 136.9 N (nearest tenth)

4 0

3 years ago