A particle of mass $$m$$ moves along line PC with velocity $$v$$ as shown. What is the angular momentum of the particle about P?

Two spheres of the same material have radii $$1$$ $$m$$ and $$4$$ $$m$$ and temperatures $$4000$$ $$K$$ and $$2000$$ $$K$$ respectively. The ratio of the energy radiated per second by the first sphere to that by the second is

If suddenly the gravitational force of attraction between Earth and a satellite revolving around it becomes zero, then the satellite will

Energy required to move a body of mass $$m$$ from an orbit of radius $$2R$$ to $$3R$$ is