Physics

Problem

A small asteroid of mass

m

moves directly towards a planet of mass

M

. Its speed is

v_{0}

when it is at a distance

5R

from the planet’s centre (

R

is the planet’s radius). Neglect all forces except the planet’s gravity. Which expression gives its speed

v

when it reaches a distance

2R

from the planet’s centre? a)

v^{2}=v_{0}^{2}+\dfrac{5GM}{3R}

v^{2}=v_{0}^{2}+\dfrac{3GM}{5R}

v^{2}=v_{0}^{2}+\dfrac{7GM}{5R}

v^{2}=v_{0}^{2}+\dfrac{3GM}{10R}