The earth $E$ moves in an elliptical orbit with the sun $S$ at one of the foci as shown in the figure. Its speed of motion will be maximum at the point:

The period of revolution increases in the order of:

Which of the following orbits is a possible orbit for a planet?

The figure shows the motion of a planet around the sun in an elliptical orbit with the sun at the focus. The shaded areas $A$ and $B$ are also shown in the figure,which can be assumed to be equal. If ${t_1}$ and ${t_2}$ represent the time taken for the planet to move from $a$ to $b$ and $d$ to $c$ respectively,then:

Consider a planet moving around a star in an elliptical orbit with period $T$. The area of the elliptical orbit is proportional to ...........

$A$ geostationary satellite is orbiting the earth at a height of $4R$ above the surface of the earth, where $R$ is the radius of the earth. Another satellite is orbiting the earth at a height $1.5R$ from the surface of the earth with periodic time $T$ in hours. The value of $T$ in hours is: