Posted by Abbey on Friday, April 16, 2010 at 3:07pm.
Projectile motion: Let's suppose you throw a ball straight up with an initial speed of 50 feet per second from a height of feet.
a) Find the equation that describes the motion as a function of time.
My answer was x = 0 and y=16t^2+50t+6
b) How long is the ball in the air?
This is the part I need help on. Can I put the y equation into my graphing calculator to solve for t?

Math  bobpursley, Friday, April 16, 2010 at 3:13pm
you can, but it is not necessary.
when it returns to ground, y=0
0=16t^2+50t+6
16t^250t6=0
using the quadratic equation...
t= (50+sqrt(2500+384)/32
t=(50+sqrt 53.7)/32=103.7/32=3.24sec
Your graphing calc may have a subrouting to solve quadratic equations, many do.
check my work.