Well when she hits the water h=0 so
2t^2-t-6=0 factor
2t^2-4t+3t-6=0
2t(t-2)+3(t-2)=0
(2t+3)(t-2)=0, since t>0
t=2 seconds...
However it should be noted that h(t)=-2t^2+t+6 implies that
v(t)=dh/dt=-4t+1 and
a(t)=dv/dt=-4
Since this is a free fall equation, this would suggest that the acceleration due to gravity is -4, whether that is supposed to be -4ft/s^2 or -4m/s^2, it certainly is not on this planet! :D If it is -4ft/s^2 it could be on the Moon or if it is -4m/s^2 it could be on Mars.
