Answer:
D.
Explanation:
But this just happen for big stars, like more than 20x the Sun mass.
Shortly: A nebula is a cloud of gas and dust, the material starts to be acummuleted and became a protostar (is like a big planet, almost a star). With enought mass this is a star, burn hydrogen and transform it in Helium.
This occurs in Main Sequence, is about almost all the life time of a star. Then starts the lack of hydrogen. Gravity compress everything, pressure goes up and heat all. Too much energy, Helium get burned and the star grews fast, became a Red Giant. Time pass and the fuel is over, no more making fusion, gravity compress the star, too much strenght, colapses, neutron star.
If it have pretty mass, ok. If have more than like 2x Sun mass, became a blackhole.
Answer:
Explanation:
Let the volume of air be V. at atmospheric pressure, that is 10⁵ Pa
At 20 m below surface pressure will be
atmospheric pressure + hdg
10⁵ + 20 x 9.8 x 1000 = 2.96 x 10⁵Pa
At this pressure volume V becomes V/ 2.96
This volume will last 1/2.96 times time that is 60/2.96 = 20.27 minutes.
Ignoring the air resistance it will take about 3 seconds for the object to reach the ground.We know that the acceleration due to gravity is 10m/s2.
We also know that the final velocity is 30 m/s while the initial velocity is 0 m/s
we can use the formulae for acceleration to calculate the time taken/
(final - initial velocity)/timetaken=10
(30-0)/timetaken=10
timetaken =30/10=3 seconds
Renewable energy
<u>Advantages :-</u>
1. Easily regenerate
2. Boost economic growth
3. Easily available
4. Support environment
5. Low maintenance cost
<u>Disadvantages :-</u>
1. Weather dependency
2. High installation cost
3. Noise caused by wind energy
4. Fluctuation problem (solar)
5. Intermittency issue (wind)
Non-renewable energy
<u>Advantages :-</u>
1. Concentrated energy source
2. Reliable energy source
3. Can be built anywhere
4. No radioactive waste
<u>Disadvantages :-</u>
1. Produces greenhouse gases
2. Contributes to global warming
3. Produces acid rain
4. Harmful to environment when they are burnt
<em>I hope this helps.....</em>
