Consider an airless, non-rotating planet of mass M and radius R. and electromagnetic launcher standing on the surface of this planet shoots a projectile with initial velocity v0 directed straight up. Unfortunately, due to some error, v0 is less than the planet's escape velocity ve; specifically, v0 = 0.762ve. Unable to escape the planet's gravitational pull, the projectile rises to a maximal height h above the ground, then falls back to the ground. Calculate the ratio h/R of the projectile's maximum height to the planet's radius.

Respuesta :

Given data:

The mass of planet is M.

The radius of planet is R.

The initial velocity of projectile is v₀=0.762ve.

The amount of kinetic and potential energy should be equal according to conservation of energy,

[tex]\begin{gathered} KE=PE \\ \frac{1}{2}mv^2_e=\frac{GMm}{R}^{}_{} \\ R=\frac{GM^{}_{}}{v^2_e} \end{gathered}[/tex]

The escape velocity is given by,

[tex]v_e=\sqrt[]{\frac{2GR}{M}}[/tex]

Here, G is the universal gravitational acceleration.

The time taken to reach the maximum height will be,

[tex]\begin{gathered} v_0=gt \\ t=\frac{v_0}{g} \end{gathered}[/tex]

The maximum height reached by the projectile is given by,

[tex]\begin{gathered} h=v_0t+\frac{1}{2}gt^2 \\ h=v_0(\frac{v_0}{g})+\frac{1}{2}g(\frac{v_0}{g})^2 \\ h=\frac{v^2_0}{g}_{}+\frac{1}{2}\frac{v^2_0}{g}_{} \\ h=\frac{3}{2}\frac{v^2_0}{g}_{} \\ h=\frac{3}{2}R \\ \frac{h}{R}=1.5 \end{gathered}[/tex]