The equation for the motion of a projectile fired straight up at an initial velocity of 64 ft/s is h = 64t - 16t^2, where h is the height in feet and t is the time in seconds. Find the time the projectile needs to reach its highest point. How high will it go?
a.2 s; 64 ft
c.3 s; 82 ft
b.1 s; 56 ft
d.4 s; 56 ft

Question

The equation for the motion of a projectile fired straight up at an initial velocity of 64 ft/s is h = 64t - 16t^2, where h is the height in feet and t is the time in seconds.  Find the time the projectile needs to reach its highest point.  How high will it go?
a.2 s; 64 ft
c.3 s; 82 ft
b.1 s; 56 ft
d.4 s; 56 ft

anonymous · Answer

The highest point... So we need to find the critical numbers.

anonymous · Answer

Do you know how to differentiate a function?

anonymous · Answer

We want to find values of $t$ such that $h'(t) = 0$.  Then we plug them in to find the highest one.