Suppose, initially the ladder is so close that height of the ladder, which is 10 m to the point at which its upper end has reached.
When we pull the bottom of the ladder to such a place that it has come down by 7 m and its upper end is now 3 m from the ground. If we take the base y m, then
Using Pythagorus theorem,
y2 = 10^2 - 3^2 = 100 - 9 = 91
y = 9.54 m
The speed by which ladder was pulled was 2 m/min
So time taken to cover 9.54 m woulds be 4.77 min
As the ladder has come down by 7 m in 4.77 min, its speed for coming down was 7/4.77 = 1.47 m/min
