A 18-foot ladder is leaning against a building. If the bottom of the ladder is sliding along the pavement directly away from the building at 2 ft/sec, how fast is the top of the ladder moving down when the foot of the ladder is 2 feet from the wall?

ft/sec.

Step-by-step explanation:

We have been given that a 18-foot ladder is leaning against a building. The bottom of the ladder is sliding along the pavement directly away from the building at 2 ft/sec. We are asked to find find how fast is the top of the ladder moving down when the foot of the ladder is 2 feet from the wall.

First of all, we will draw a graph to represent the given information as shown in the attachment.

Now, we will use Pythagoras theorem as:

Now, we will find derivative with respect to time.

Let us find value of x, when y is 2 using Pythagoras theorem.

Upon substituting our given values in derivative function, we will get:

Therefore, the top of the ladder is moving down at a rate of feet per second.

the answer to this question is "motor unit"