The equation of motion (for the height of the ball) is h(t) = -16t^2 + 56t. Please note that you must use the symbol " ^ " to indicate exponentiation.
This quadratic function could be graphed easily. Factoring h(t) = -16t^2 + 56t, we get h(t) = t(-16t + 56). We can obtain the horiz. intercepts by setting this function equal to zero and solving for t. One value is t=0; the other is t=(7/2). If you graph this parabola, you can read off from your graph the t value at which the ball reaches its highest point. That t value is halfway between t=0 and t=(7/2).
Alternatively, you could find the vertex of this parabola as a t-value. This t-value is the answer to this problem.
Recall that at the vertex, t = -b/a, where, in this case, b=56 and a=-16.
Calculate:
t = -56/(-16). The units of measurement must be "sec."
