Question

A planet is revolving around sun in elliptical orbit. Maximum & minimum distance of planet from sun are respectively 1.6 × 10¹² m and 6 × 10¹⁰ m. Find minimum speed if maximum speed of planet is 8 × 10⁴ m/s?

(1) 3 × 10⁴ m/s (2) 3 × 10³ m/s (3) 8 × 10³ m/s (4) 4 × 10⁴ m/s

Answer 1

Correct answer is 3) 8\(\times 10^3 m/s\) 

L = mv_maxr_min = m v_min × r_max 

 8 × 10⁴ × 6 × 10¹⁰ = v_min × 1.6 × 10¹² 

v_min = 3 × 10³ m/s