<PRE><B>Question 737411</B>
A lemming runs from a point A to a cliff at 4m/s,jumps over the edge at B and falls at C at an average speed of 25 m/s,
if the total distance from A to C is 500 metres and the time taken for the journey is 41 seconds, find the height Bc of the cliff.
:
let c = height of the cliff
total A to C distance given as 500m
(500-c) = distance from A to B
:
Write a time equation; time = dist/speed
:
Run time + fall time = 41 sec
{{{((500-c))/4}}} + {{{c/25}}} = 41
multiply by 100, clears the denominators, 
25(500-c) + 4c = 4100
12500 - 25c + 4c = 4100
-25c + 4c = 4100 - 12500
-21c = -8400
c = -8400/-21
c = 400 meter clif</PRE>