The answer is b. According to the law of conservation of energy, energy can never be created nor destroyed, only transferred from one form to another.
Answer:

Explanation:
Given:

As we know that
Force=Mass * Acceleration
Putting the value of mass and Acceleration we get ,


Therefore Net force is :
the amplitude of a sound wave determines its loudness or volume. A larger amplitude means a louder sound, and a smaller amplitude means a softer sound. In Figure 10.2 sound C is louder than sound B. hope i helped!
(sorry if wrong)
Gas Clouds (of Hydrogen), starts contracting under the influence of gravitational pull of gas.
As it's contracting, it's pressure & temperature increases, it is called "Protostar" now.
When Temperature become sufficiently high (4 million C), Nuclear fusion starts, & large amount of energy releases.
Energy Travels to star's surface and is radiated in the form of light, heat & EM Radiation.
The contraction of star stops only when "Inward Gravitational pull" is balanced by "Outward Radiant Energy". At this time, star becomes stable in size & temperature.
Contraction continues, 'causes star's outer region to 'boil' & 'expand'. At this stage, it becomes brightest, red giant.
As fuel burns, helium nuclei fuses & form Carbon nuclei further to silicon & further to Iron Nuclei by progressive Nuclear Fusions. At all this stages, star was very unstable.
Star end it's life in many different way & it depends on it's mass, whether it ends as "White Dwarf", "Neutron Star" or "Supernova"
This was a short note on life story of star. <span>Hope this helps!</span>
Maybe when you ice-skate 10 times per second around a 1-foot circle.