Pls help me with this question its due tomorrow and I can't find the A person jumped 50cm, the hang time for the jump was 0.778 seconds, calculate a value for the acceleration due to gravity. What is the percent error in the value for acceleration you found? (Solve it without factoring in the air)

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?