Question

Which equation would best help solve the following problem?



Hideki throws a baseball ball upward with an initial velocity of 12 m/s. When he throws the ball, it is 2 m above the ground. How long will it take the ball to hit the ground?

a. –16t2+ 12t + 2 = 0
b. –4.9t2 + 12t + 2 = 0
c. –4.9t2 + 12t = 2
d. 4.9t2 + 12t + 2 = 0

Answer 1

@mathmate

Answer 2

@Michele_Laino

Answer 3

The general equation is

\[\Large h = -\frac{g}{2}t^2 + v*t + s\]

h = height at time t
g = acceleration of gravity (g = 9.8 m/s^2 approximately)
v = initial velocity
s = initial height

Answer 4

I need an example of this.... I don't understand

Answer 5

ok let's say

initial velocity is v = 10 m/s
initial height is s = 12 m

that would mean the height equation is

\[\Large h = -\frac{g}{2}t^2 + v*t + s\]
\[\Large h = -\frac{9.8}{2}t^2 + 10t + 12\]
\[\Large h = -4.9t^2 + 10t + 12\]

Answer 6

solving h(t) = 0 will give you the time values when the object is on the ground