A person standing on a vertical cliff a height h above the lake wants to jump into the lake but notices a rock just at the surface level with its furthest edge a distance s from the shore .The person realizes that with a running start it will be possible to just clear the rock, so the person steps back from the edge a distance d and starting from the rest ,runs at an acceleration that varies in time according to ax=b1t and then leaves the cliff horizontally. The person just clears the rock.

Question

A person standing on a vertical cliff a height h above the lake wants to jump into the lake but notices a rock just at the surface level with its furthest edge  a distance s from the shore .The person realizes that with a running start it will be possible  to just clear the rock, so the person steps back from the edge a distance d and starting from the rest ,runs at an acceleration that varies in time according to  ax=b1t and then leaves the cliff horizontally. The person just clears the rock. 
Find s in terms of the given quantities d ,b1,h,and acceleration due to gravity g.You may  neglect all air resistance.

bobpursley · Answer

time to fall h meters
h=1/2 g t^2 or
t= sqrt(2h/g)

now, time to traverse that distance horizontally in time t.

s=v*t solve for v

but v^2=2*d*a1
or
s= sqrt(2d*a1)*sqrt(2h/g)
s=sqrt(2d*a1*2h/g)

check my thinking

Anonymous · Answer

Which of the substances Exhibited the greatest molecular forces between water,acetone,methylated spirits and sunflower oil???