Remote sensing satellites move in an orbit that is at an average height of about $500 \,km$ from the surface of the earth. The camera onboard one such satellite has a screen of area $A$ on which the images captured by it are formed. If the focal length of the camera lens is $50 \,cm$, then the terrestrial area that can be observed from the satellite is close to …………… $A$

A planet is moving in an elliptical orbit around the sun. If $T, V, E$ and $L$ stand respectively for its kinetic energy, gravitational potential energy, total energy and magnitude of angular momentum about the centre of force, which of the following is correct ?

A satellite $S$ moves around a planet $P$ in an elliptical orbit as shown in figure. The ratio the speed of the satellite at point $a$ to that at point $b$ is

The maximum and minimum distances of a comet from the sun are $8 \times {10^{12}}\,m$ and $1.6 \times {10^{12}}\,m$. If its velocity when nearest to the sun is $60\, m/s$, what will be its velocity in $m/s$ when it is farthest 

The relative uncertainty in the period of a sateilite orbiting around the earth is $10^{-2}$. If the relative uncertainty in the radius of the orbit is negligible, the relative uncertainty in the mass of the earth is