A 15 ft ladder leans against a wall. The bottom of the ladder is 4 ft from the wall at time t=0 and slides away from the wall at a rate of 2ft/sec.
Find the velocity of the top of the ladder at time t=1.
If the bottom is x feet from the wall,
and the top is y feet up the wall, then
x^2 + y^2 = 15^2
x dx/dt + y dy/dt = 0
Now plug in your numbers to find dy/dt