Answer to Question #40942 in Mechanics | Relativity for alzahra

Question

a) A dentistry student is running with a constant acceleration until she reached a max
speed of 5m/s. If she suddenly sees a wall 20 m in front of her, how long will it
take her to come to a complete stop just before she reaches the wall, what was her
acceleration?
b) If the same student decided to check what is behind the wall by stepping 5 meters
back and throwing a rock so that just clears the 2-m high wall. What should be the
initial velocity (magnitude and direction) by which she must throw the rock, so
that it just clears the wall at its max height of trajectory?