A cliff diver falls forward from a cliff 130 feet above the ground. His position function is given by s(t) -16t^2 +130, where t is measured in seconds and s is measured in feet.

After how many seconds will he be traveling at
-40 ft/s?

Question

A cliff diver falls forward from a cliff 130 feet above the ground. His position function is given by s(t) -16t^2 +130, where t is measured in seconds and s is measured in feet.

After how many seconds will he be traveling at 
-40 ft/s?

anonymous · Answer

Take the derivative of s(t) and set it equal to -40 ft/s then solve for time.

anonymous · Answer

Thanks, I got 1.25 sec. 
How about how far he would have fallen by that time?

anonymous · Answer

you substitute t=1.25 into your derivative

anonymous · Answer

substitute it into v'(t)?

anonymous · Answer

or s(t) since it said "how far?"

anonymous · Answer

How do I find the average velocity for [0, 2]?