I believe the correct answer is D
<span>B. If the temperature of a solid is increased, the solid expands and its volume increases.</span>
Answer:
2653 turns
Explanation:
We are given that
Diameter,d=2 cm
Length of magnet,l=8 cm=
1m=100 cm
Magnetic field,B=0.1 T
Current,I=2.4 A
We are given that
Magnetic field of solenoid and magnetic are same and size of both solenoid and magnetic are also same.
Length of solenoid=
Magnetic field of solenoid

Using the formula

Where 

<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.
Answer:
option ( a ) is correct .
Explanation:
Escape velocity on the earth = √ ( 2 GM / R )
where G is universal gravitational constant , M is mass of the earth and R is radius .
V₀ = √ ( 2 GM / R )
escape velocity on the planet where mass is equal is earth's mass and radius is 4 times that of the earth
Radius of the planet = 4 R
escape velocity of planet = √ ( 2 GM / 4R )
= .5 x √ ( 2 GM / R )
= .5 V₀
option ( a ) is correct .