A planet revolves around a massive star in a highly elliptical orbit. Is its angular momentum conserved over the entire orbit?

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.

Suppose there existed a planet that went around the sun twice as fast as the earth.What would be its orbital size as compared to that of the earth?

The electron in a hydrogen atom revolves with a velocity 4.13 times10^16 rad/sec in an orbit of radius 5.29 times10^11 m. Calculate its angular momentum (given.m =9.11 times10^(-31) kg.)

The nearest star to our solar system is 4.29 light years away. How much is this distance in terms of parsecs? How much parallax would this star (named Alpha Centauri) show ,when viewed from two locations of the Earth six months apart* in its orbit around the Sun?

An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate, its speed if it takes 24 hours to revolve around the earth.

How will you ‘weigh the sun', that is estimate its mass? The mean orbital radius of the earth around the sun is 1.5 xx10^8 km.