Leyla drops a penny from a height of 150 m. how long will it take the penny to hit the ground? use the formula h(t)=−4.9t2+vot+h , where vo is the initial velocity and h is the initial height. round to the nearest tenth of a second. __s

When the penny hits the ground, h will = 0.

So:  Set h(t) = 0 = -4.9t^2 + 0t + 150 m

Then 4.9t^2 = 150, and so t^2 = sqrt(150 / 4.9)   =    plus or minus 5.53 sec.

We can use only the positive root, as we're measuring time.

t = 5.5 sec (answer)

Could you make it more clear?