<h2>Answer: Gravitational attraction
</h2>
Gravity force causes the clouds of dust and gas to form a protostar. As this <u>attraction force</u> is responsible for gathering and compressing the existing elements in the cloud of gas and dust, heating them during this process.
Then, when the amount of material accumulated by gravitational contraction is large enough, and the temperature and pressure reached high enough, the <u>nuclear fusion</u> process will begin.
To understand it better: The hydrogen nuclei will begin to fuse, generating helium nuclei in the process and releasing huge amounts of energy.
It should be noted that the protostars radiate half of the energy contributed by the gravitational collapse and the other half is invested in heating its core.
The volume of the balloon will halve
Explanation:
Boyle's law states that for an ideal gas kept at constant temperature, the pressure of the gas is proportional to its volume. Mathematically,

where
p is the gas pressure
V is the volume
The equation can also be rewritten as

And if we apply it to the gas inside the balloon in this problem (assuming its temperature is constant), we have:
is the initial pressure at sea level (the atmospheric pressure)
is the initial volume
is the final pressure
is the final volume
Substituting into the equation, we find:

Which means that the volume of the balloon will halve.
Learn more about ideal gases:
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784 Newtons or 176.37 lbs
(a) Her distance from the starting location is 21.05 m.
(b) The length of the path she skated is 21.05 m.
<h3>
Distance of the skater from the starting position</h3>
The distance around a complete circular path is calculated as 2πr.
The distance for a half circle is calculated as ¹/₂ x 2πr = πr
Distance from the starting location = π x 6.7 m = 21.05 m
The length of the path she skated is the same as her distance from the starting location = 21.05 m.
Learn more about distance round a circle here: brainly.com/question/3100527
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Answer: 
Explanation:
We know that force acting on an object due to Earth's gravity on the surface is given by:

where g is the acceleration due to gravity, r would be radius of Earth, M is the mass of Earth and G is the gravitational constant.
It is given that at pole, g = 9.830 m/s² and r = 6371 km = 6371 × 10³ m



Hence, Earth's mass is 