One ball is dropped from a cliff. A second ball is thrown down 1.00 s later with an initial speed of 40.0 ft/s. How long after the second ball is thrown will the second ball overtake the first?

Answer 1

I could swear I did this one yesterday :(

ball 1
d = distance down
d = .5 g (t+1)^2

ball 2
d = 40 t + .5 g t^2

so
.5 g (t^2 + 2 t + 1) = 40 t + .5 g t^2
put in whatever you use for g (9.81, 9.8 or 10) and solve the quadratic