Gravitation - Result Question 8
8. The largest and the shortest distance of the earth from the sun are $r_1$ and $r_2$. Its distance from the sun when it is at perpendicular to the major-axis of the orbit drawn from the sun is
[1988]
(a) $\frac{r_1+r_2}{4}$
(b) $\frac{r_1+r_2}{r_1-r_2}$
(c) $\frac{2 r_1 r_2}{r_1+r_2}$
(d) $\frac{r_1+r_2}{3}$
Topic 2: Newton’s Universal Law of Gravitation
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Answer:
Correct Answer: 8. (c)
Solution:
- (c) Applying the properties of ellipse, we have
$\frac{2}{R}=\frac{1}{r_1}+\frac{1}{r_2}=\frac{r_1+r_2}{r_1 r_2}$
Instant position
$R=\frac{2 r_1 r_2}{r_1+r_2}$
