A lion is stalking an antelope that is running at a speed of 7m/s. At the moment the antelope passes the lion, she gives chase and accelerates at a rate of 5m/s^2. How long will it take the lion to catch up to the antelope?

Antelope: uniform motion = > V = d/t = > d = Vt = 7m/s * t

Lion: uniformly accelerated motion, with initial velocity = 0 = > d = [1/2]a*t^2 = [1/2]*[5m/s^2]*t^2

7*t = 2.5*t^2=> 2.5t^2 - 7t = 0 = > t (2.5t - 7) = 0

2.5t - 7 = 0 = > t = 7/2.5 = 2.8 m/s^2