Quadratic Equation

Question

An object is projected vertically in the air with a velocity of 62 m/s. Using the formula h= -4.9t^2+v0t, where h represents the height (m) and t represents time (s),

When will the object be 180m from the ground

Answer 1

180 = -4.9t^2 + 62t

4.9t^2 -62t + 180 = 0

use the quadratic formula

t = 62/9.8 + or - (1/9.8)sqr(62^2 -4(4.9)(180)) = about 4.51 or 8.14 seconds.

it reaches a maximum height in 62/9.8 = about 6.33 seconds

in about 4.51 seconds the object is going upwards and reaches 180 meters high

then in about 8.14 seconds it falls down and again reaches 180 meters from the ground