What must her minimum speed be just as she leaves the top of the cliff so that she will miss the ledge at the bottom, which is L = 2.50{\rm m} wide and h = 9.50{\rm m} below the top of the cliff?

Answer 1

how long to fall 9.5 m ?

h = 9.5
speed down at bottom, v = sqrt (2 g h)
= 13.65 m/s
so average speed down = 6.83 m/s
so time down = 9.5/6.83 = 1.39 second fall
u t = d

u ( 1.39) = 2.5
u = 1.8 m/s