Question

very very crooked and insecure the wall for yards round looking as if it had been smoothed down with a rake ​

Answer 1

Answer:

Consider a satellite of mass m moving around the earth with velocity vo in an orbit of radius r. Because of gravitational pull of the earth, the satellite has potential energy which is given by

U =-(GMm) /(r)

The kinetic energy of a satellite due to its orbital motion is

K= (1/2) m vo2

=(1/2) m(GM/r) (because vo = √(GM)/(r)

Total energy of the satellite is

E =(U + K)

=-(GMm/r) +(1/2) (GMm/r)

Or E = - (GMm/2r)

=-(GMm/2(R+h))

The total energy of the satellite is negative. It indicates that the satellite is bound to the earth by means of attractive gravitational force,

At infinity the potential energy is 0. Therefore negative total energy means that in order to send the satellite to infinity, it must be given extra energy (to make total energy 0), otherwise it will continue revolving in a closed orbit.

For circular orbit, E =-K and U=-2K = 2E

Given Kinetic energy = 800J

In order to calculate formula used is: - KE = (1/2) mvo2 = (1/2) m(GM/r)

= (1/2) (GMm)/(r)

Potential Energy = U =-(GMm)/(r)

Total energy of satellite E= (K+U)

=[(1/2) mvo2 + -(GMm)/(r)]

=-(GMm)/(2r)