# A ladder 5m long is standing vertically, flat against a vertical wall, while its lower end in on the horizontal floor. ... Find the speed at which the upper end is moving down the wall 4 seconds after the lower end has left the wall ?

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A ladder 5m long is standing vertically, flat against a vertical wall, while its lower end in on the horizontal floor. The lower end moves horizontally away from the wall at a constant speed of 1m/s while the upper end stays in contact with the wall. Find the speed at which the upper end is moving down the wall 4 seconds after the lower end has left the wall.

A ladder 5m long is standing vertically, flat against a vertical wall, while its lower end in on the horizontal floor. The lower end moves horizontally away from the wall at a constant speed of 1m/s while the upper end stays in contact with the wall. Find the speed at which the upper end is moving down the wall 4 seconds after the lower end has left the wall.

##### 1 Answer

Speed is

#### Explanation:

Using

#{(x_o = 0),(dot x = 1),(y_0 = 5):}#

The relationship between

# x^2 + y^2 = 25#

Differentiate wrt

So **speed** is

**EDIT** :

I found this image on YouTube which might help you understand what is going on. NB the numbers are different, but the basic idea is the same: