Halliday, Resnick & Walker — Gravitation: Problem Problem_34

Figure 13.23 gives the potential energy function \( U(r) \) of a projectile, plotted outward from the surface of a planet of radius \( R_s \). If the projectile is launched radially outward from the surface with a mechanical energy of \( -2.0 \times 10^9 \text{ J} \), what are (a) its kinetic energy at radius \( r = 1.25 R_s \) and (b) its turning point (see Module 8.3) in terms of \( R_s \)?