dy/dx = -9.8t + 68.6
= 0 for a max of y
9.8t = 68.6
t = 7
after 7 sec it will have a max of
-4.9(49) + 68.6 or 240.1 ft
or
complete the square on
y = -4.9 t^2 + 68.6 t
= -4.9(t^2 - 14t + 49 - 49)
= -4.9(t-7)^2 + 240.1
vertex is (7, 240.1) , and the parabola is downward
Max is 240.1 , when t = 7
An object is fired vertically upward with an initial speed of 68.6 meters/second. After t seconds, the height is shown by
y = -4.9 t^2 + 68.6 t meters. Given that this object has an initial speed of 68.6 m/s, what is the maximum height it will reach? How long did it take the rocket to reach the maximum height?
1 answer