Describe the method for drawing an ellipse and explain foci of ellipse, midpoint, semi major axis.
Select two points $\mathrm{F}_{1}$ and $\mathrm{F}_{2}$.
A string has its ends fixed at $\mathrm{F}_{1}$ and $\mathrm{F}_{2}$.
With the tip of a pencil stretch the string taut and then draw a curve by moving the pencil keeping the string taut throughout.
The closed curve you get is called an ellipse.
For any point $\mathrm{T}$ on the ellipse, the sum of distances from $\mathrm{F}_{1}$ and $\mathrm{F}_{2}$ is a constant. $\mathrm{F}_{1}$ and $\mathrm{F}_{2}$ are called the foci.
Join the points $\mathrm{F}_{1}$ and $\mathrm{F}_{2}$ and extend the line to intersect the ellipse at points $\mathrm{P}$ and $\mathrm{A}$ as shown in figure. The midpoint of the line $PA $is the centre of the ellipse $"O"$.
The length $\mathrm{PO}=\mathrm{AO}$ is called the semi major axis of the ellipse.
If the earth suddenly shrinks to $\frac{1}{64}$ th of its original volume with its mass remaining the same, the period of rotation of earth becomes $\frac{24}{ x } h$. The value of $x$ is $.......$
If the distance of the earth from Sun is $1.5 \times 10^6\,km$. Then the distance of an imaginary planet from Sun, if its period of revolution is $2.83$ years is $.............\times 10^6\,km$
A satellite $A$ of mass $m$ is at a distance of $r$ from the centre of the earth. Another satellite $B$ of mass $2m$ is at a distance of $2r$ from the earth's centre. Their time periods are in the ratio of
An earth satellite $S$ has an orbit radius which is $4$ times that of a communication satellite $C$. The period of revolution of $S$ is ........ $days$
Let the speed of the planet at the perihelion Pin Figure be $v_{p}$ and the Sun-planet distance $SP$ be $r_{ P }$ Relate $\left\{r_{P}, v_{P}\right\}$ to the corresponding quantities at the aphelion $\left\{r_{A}, v_{A}\right\} .$ Will the planet take equal times to traverse $B A C$ and $C P B ?$