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3 years ago

What are greenhouse gases? Can you name any?

1 answer:

7 0

Greenhouse gasses in the upper atmosphere trap heat from the Earth and reflect it back down rather than allow it to escape. This makes Earth progressively warmer.

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Most of the stars in the Milky Way will end their lives as

umka21 [38]

<span> </span>Most of the stars in the Milky Way will end their lives as white dwarfs

4 0

3 years ago

Read 2 more answers

HELP PLEASE 20 POINTS SHOW WORK, ALL EQUATIONS

nataly862011 [7]

Answer:

s = 3 m

Explanation:

Let t be the time the accelerating car starts.

Let's assume the vehicles are point masses so that "passing" takes no time.

the position of the constant velocity and accelerating vehicles are

s = vt = 40(t + 2) cm

s = ½at² = ½(20)(t)² cm

they pass when their distance is the same

½(20)(t)² = 40(t + 2)

10t² = 40t + 80

0 = 10t² - 40t - 80

0 = t² - 4t - 8

t = (4±√(4² - 4(1)(-8))) / 2(1)

t = (4± 6.928) / 2 ignore the negative time as it has not occurred yet.

t = 5.464 s

s = 40(5.464 + 2) = 298.564 cm

300 cm when rounded to the single significant digit of the question numerals.

7 0

3 years ago

Monochromatic light of a given wavelength is incident on a metal surface. However, no photoelectrons are emitted. If electrons a

mrs_skeptik [129]

Answer:

Light of a shorter wavelength should be used.

Explanation:

This is studied in the phenomenon called photoelectric effect, in which light is able to release electrons from a metal, said electrons are called photoelectrons .

The experiments that have been carried out show that <u>increasing or decreasing the intensity of the light will not cause the photoelectrons to be emitted</u>, what will cause the photoelectrons to be emitted is to increase the frequency of the incident light.

And a higher frequency corresponds to a shorter wavelength according to the equation:

$f=\frac{c}{\lambda}$

(where $f$ is frequency, $c$ the speed of light, and $\lambda$ the wavelength)

So the answer is that the wavelength of the light must be shortened to cause the emission of electrones.

4 0

4 years ago

How can citizen -scientists help with the prediction of future earthquakes

iVinArrow [24]

Answer:

Avoid downed power lines and stay away from buildings and bridges from which heavy objects might fall during an aftershock. Stay away until local officials tell you it is safe. A tsunami is a series of waves that may continue for hours. Do not assume that after one wave the danger is over.

3 0

4 years ago

A bullet fired horizontally hits the ground in 0.5 sec. If it had been fired with a much higher speed in the same direction, and

stira [4]

Answer:

3. 0.5 sec.

Explanation:

A bullet fired horizontally follows a projectile motion, which consists of two independent motions:

- A horizontal motion with constant speed

- A vertical motion with constant acceleration, g = 9.8 m/s^2, towards the ground

The time taken for the bullet to reach the ground can be calculated just by considering the vertical motion:

$y(t) = h + v_{0y} t - \frac{1}{2}gt^2$

where y is the vertical position at time t, h is the initial height, and $v_{0y}$ is the initial vertical velocity of the bullet.

Since the bullet is fired horizontally, $v_{0y}=0$ . So the equation becomes

$y(t) = h - \frac{1}{2}gt^2$

And the time that the bullet takes to reach the ground can be found by requiring y=0 and solving for t:

$t=\sqrt{\frac{2h}{g}}$

As we can see, in this equation there is no dependance on the initial speed of the bullet: therefore, if the bullet is fired still horizontally but with a different speed, it will still take the same time (0.5 s) to reach the ground.

4 0

3 years ago