Explanation:
spectral lines or signatures of elements depend on temperature, the temperature of the sun is about 5800 K.
at this temperature most calcium atoms are excited to higher energy states than hydrogen atoms and this means that calcium atoms are gonna have more signatures than the atoms of hydrogen.
the statement that the sun shows weak hyrogen lines and strong calcium line is wrong because at the sun's temperature most of the hydrogen atoms are in lower energy states while calcium atoms are in higher energy states hence calcium has more or ''strong'' lines than hydrogen.
Both valves are closed during the power stroke.
While the fuel is burning in the cylinder, you want
all the force of the expanding gases to push the
piston down ... you don't want any of the gases
or their pressure escaping.
If either of the valves was open, even just a crack,
then part of the gases would go blooey out the valve,
and some pressure would be lost that's supposed to be
pushing the piston.
Answer:
Constructive interference
Explanation:
Here, the medium is same, same wavelength, same frequency, same amplitude and same direction of propagation.
Let the intensity of waves be I which is same for both
The formula for the net intensity is
where, Ф be the phase difference
So, 
Here, IR is maximum so the interference is constructive in nature.
Answer:
10s
Explanation:
If it took Beatrice 25 seconds to complete the race
Distance = 100 meter
Beatrice speed = 100/25
= 4m/s
If Alice runs at a constant speed and crosses the finish line $5$ seconds, she must have completed the race in 20s (25 -5).
Her speed where constant
= 100/20
= 5 m/s
It would take Alice
= 50/5
= 10s
It would take Alice 10s to run $50$ meters.
Answer:
D = 25 miles
Explanation:
To solve this problem, we just need to know how much time it took both bicyclists to collide and that will be the same amount of time that the bee flew at 25miles per hour. With those values we could calculate the distance it traveled.
Since both bicyclists collide, we know that Xa=Xb, so:
Xa = V*t = 10*t and Xb = 20 - V*t = 20 - 10*t
10*t = 20 - 10*t Solving for t:
t = 1 hour Now we can calculate the distance for the bee:
D = Vbee * t = 25 * 1 = 25 miles
