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PART - 1 CH - 7 Gravitation — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysicsPART - 1 CH - 7 Gravitation4 Marks
Question
A comet orbits the sun in a highly elliptical orbit. does the comet have a constant (a) linear speed, (b) angular speed, (c) angular momentum, (d) kinetic energy, (e) potential energy, (f) total energy throughout its orbit? Neglect any mass loss of the comet when it comes very close to the sun.
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Answer

(a) According to Kepler's second law, when the comet is near the sun, it moves fast. But when the planet
is far away, it moves slowly. Therefore, we can say that the linear motion of the comet doesn't remain constant.
(b) The angular speed of the comet also changes slightly.
(c) As per the rules, the angular momentum of the comet is conserved.
(d) The linear speed of the rotating comet is changing from time to time hence its kinetic energy also changes
continuously.
(e) The value of potential energy depends on the distance from the Sun to the Earth. This is the reason why
the potential energy keep changing in an elliptical orbit as the distance between the Sun and the comet changes continously.
(f) We know that mechanical energy i.e., total energy is equal to the sum of kinetic energy and potential energy. Hence this value always remains constant according to the law of conservation of energy. The total energy of the comet remains constant.

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