Question

Which of the following are not correct?

• A. The escape velocity for the Moon is $6km$ $s^{-1}$
• B. The escape velocity from the surface of Moon is $v$. The orbital velocity for a satellite to orbit very close to the surface of Moon is $v/2$
• C. When an earth satellite is moved from one stable orbit to a further stable orbit, the gravitational potential energy increases
• D. The orbital velocity of a satellite revolving in a circular path close to the planet is independent of the density of the planet.

Answer 1

Answer: (A), (D)

The correct options are
A The escape velocity for the Moon is $6km$ $s^{-1}$
D The orbital velocity of a satellite revolving in a circular path close to the planet is independent of the density of the planet.

A.The escape velocity for the Moon is $2.4km{s}^{-1}$

D.$v_0=\sqrt{\frac{2GM}{R}}=\sqrt{\frac{2G}{R}\times \frac{4}{3}\pi R^3\rho }$

or $v_0\propto \sqrt{\rho }$

so,the incorrect choices are A and D.