Question

The escape velocity of a body thrown vertically upwards from the surface of earth is
$11.2$ Km/s. If it is thrown in a direction making an angle of ${30}^0$ from the vertical, the new escape velocity will be

• A. $5.6$ Km/s
• B. $11.2$ Km/s
• C. $11.2\times \sqrt{2}$ km/s
• D. $11.2\times \frac{\sqrt{3}}{2}$ km/s

Answer 1

Answer: (B)

$11.2$ Km/s

Escape speed is given by: $v=\sqrt{2gR}$
This is obtained by conservation of energy, which is a scalar quantity. Hence doesn't depend on the directions.
So, escape speed is independent of the direction of projection and will be $11.2$ km/s only.