Answer:
B. 500 years
Explanation:
The light coming from the star and reaching us on the Earth travels with uniform motion (with constant velocity), so we can use the equation of uniform motion which relates distance covered, speed and time taken:
where
v is the speed
d is the distance covered
t is the time taken
In this problem:
is the speed at which light travels
is the distance that light has to cover from the star to the Earth
Therefore, by rearranging the equation, we can find the time:
And by converting into years, this time is
So, approximately 500 years: this means that the image we see of the star is 500 years old.
The correct answer to the question is D). Kinetic to electrical.
EXPLANATION:
Hydro electric power plants are the electricity generation plants which capture the energy of falling water to produce current.
The water present at the top of a dam has potential energy. When the water is allowed to fall from certain height, the potential energy of the water is converted into kinetic energy.
The falling water moving with high speed is allowed to fall on a turbine. The kinetic energy of the water will rotate the turbine. The turbine is attached to a generator which will produce electricity due to the electromagnetic induction.
Hence, we see that the kinetic energy of the water is converted into electric energy.
Gravitational potential energy is energy.
The unit of energy is the Joule.
1 Joule = 1 kilogram-meter² / sec²
Without counting wind resistance, They will both reach the ground at the same time. If we apply the concept of kinematics, such as the equation vf^2=vi^2 + 2ad. This equation doesn't count how big or how heavy the mass is, it only focuses on how fast where they in the start and how far are both of them from the ground. So if they both have the same distance and same initial veloctity, then they will reach the ground at the same time.
For example, Try dropping a pen and a paper(Vertically) at the same height, you'll see they'll reach the ground at the same time.
If you count wind resistance, the heavier ball will hit the ground faster, because the air molecules will resist the lighter ball compared to the heavier ball.
To solve this problem, let us recall that the formula for
gases assuming ideal behaviour is given as:
rms = sqrt (3 R T / M)
where
R = gas constant = 8.314 Pa m^3 / mol K
T = temperature
M = molar mass
Now we get the ratios of rms of Argon (1) to hydrogen (2):
rms1 / rms2 = sqrt (3 R T1 / M1) / sqrt (3 R T2 / M2)
or
rms1 / rms2 = sqrt ((T1 / M1) / (T2 / M2))
rms1 / rms2 = sqrt (T1 M2 / T2 M1)
Since T1 = 4 T2
rms1 / rms2 = sqrt (4 T2 M2 / T2 M1)
rms1 / rms2 = sqrt (4 M2 / M1)
and M2 = 2 while M1 = 40
rms1 / rms2 = sqrt (4 * 2 / 40)
rms1 / rms2 = 0.447
Therefore the ratio of rms is:
<span>rms_Argon / rms_Hydrogen = 0.45</span>
