A sun-sized star will spend most of its lifetime as a main sequence star. It is the stage in a star's life cycle where it maintains as a stable nuclear reaction. The sun in our solar system is a clear example of this. The number of years that these stars would spend at this stage depends largely on the mass of the star. These stars would fuse atoms of hydrogen forming them into helium atoms inside their cores. Fusion reactions are continually happening as days and years pass at this stage. Approximately ninety percent of the stars found in the universe are main sequence stars.
Answer:
D
Explanation:
<h2>ok so the answer is D causr d is ye</h2>
<h3><u>Answer;</u></h3>
<em>4. Only some metals are attracted by magnets; these metals are called ferromagnetic.</em>
<h3><u>Explanation;</u></h3>
- <u><em>Magnets are those materials that have the ability of producing magnetic field.</em></u> Magnets attracts materials called magnetic materials and have no effect on non magnetic materials such as wood.
- <em><u>Magnetic materials are materials that are attracted by a magnet, these includes some metal such as iron and steel.</u></em> However some metals are non-magnetic materials, these include, gold, silver, and copper among others,
- Therefore,<em><u> it would be appropriate to say that only some metals are attracted by magnets; these metals are called ferromagnetic.</u></em>
<span>BOTH CHEMICALS ARE VERY HARMFUL TO THE ENVIRONMENT. BOTH CHEMICALS ARE HARMFUL TO HUMANS AND IN SOME CASES FATAL. THESE CHEMICALS ARE COMMONLY FOUND IN OR NEAR EVERY HOUSE IN AMERICA SEEING THE CO COMES FROM OUR CARS AND TRUCKS, AND BLEACH IS ONE OF THE MOST COMMON CLEANING AGENTS USED AND CA BE FOUND IN ALMOST EVERY STORE.</span>
Answer:
They will not stop at same elevation
for v=10m/2 => h=5.1m
for v=20m/2 => h=20.4m
Explanation:
If we neglect the effects of friction in the calculations the energy if the system must be conserved. The car energy can be described as a combination of kinetic energy and potential energy:
The potential energy is due to the gravitational forces and can be describes as:
Where g is the gravitation acceleration, m the mass of the car, and h the elevation. This elevation is a relative quantity and any point of reference will do the work, in this case we will consider the base of the hill as h=0.
The kinetic energy is related to the velocity of the car as:
As the energy must be constant E will be always constant, replacing the expressions for kinetic and potenctial energy:
In the base of the hill we have h=0:
When the car stops moving we have v=0:
This two must be equal:
solving for h:
Lets solve for the two cases:
for v=10m/2 => h=5.1m
for v=20m/2 => h=20.4m
As you can see, when the velocity is the double the height it reaches goes to four times the former one.