Question

what is the work done by the force of gravity on a sattalite moving round the earth ?justify your answer​

Answer 1

• W = Force * displacement (both vectors)

• Gravity acts towards the center of the earth. So if the satellite moves in a circular orbit with center of earth as the orbit center the work done at any point is zero, since the force and the displacement are perpendicular.

• s=v.dt  

• F perpendicular to v so W=0.

• Whereas if the the orbit is some other conic section(usually elliptical) the work done by gravity changes at almost every point( there are few points where W=0). Though the total energy is constant as potential energy is changed at the expense of kinetic energy.

• Here F and vel are not perpendicular always

• so W is not always 0.

hope this answer was helpful :)