A 10-foot ladder leans against the side of the building. If the top of the ladder begins to slide down the wall at the rate of 2 ft/s, how fast is the bottom of the ladder sliding away from the wall when the top of the ladder is 8 ft off the ground?

i know this is physics relating to torque..but i just can't solve it with calculus...

Question

A 10-foot ladder leans against the side of the building. If the top of the ladder begins to slide down the wall at the rate of 2 ft/s, how fast is the bottom of the ladder sliding away from the wall when the top of the ladder is 8 ft off the ground?  

i know this is physics relating to torque..but i just can't solve it with calculus...

anonymous · Answer

|dw:1394018743991:dw|
Use the Pythagorean Theorem to establish a relationship between the height and the base of the triangle, then differentiate with respect to time (remember to use the chain rule). Then you can plug the known values for h, x, and dh/dt to solve for dx/dt.