Question

Please help! I don't understand this question! 19 pts



                                               
                         1.) A projectile launched straight up into the air with an initial velocity of 20 meters per second from a height of 10 meters. How long will it take for the projectile to hit the ground?

a.) Which formula should be used?
h(t) = -4.9t² + vot + ho
h(t) = -16t² + vot + ho

b.) What is the vo?
c.) What is the ho?
d.) Use the Quadratic Formula to solve

Answer 1

Hello,


gravity on earth :g=9.81 m/s²
$h(t)=-\frac{g*t^2}{2}+v_{0}*t+h_{0}$
9.81/2≈4.9
$v_{0}\ is\ initial\ speed$
$h_{0}\ is\ initial\ height$

Answer 1


2)
h(t)=-4.9*t²+20*t+10

To hit the ground ht(t)=0
==> -4.9*t²+20*t+10=0
Δ=20²+4*4*10=560=23,6643...²

t=(-20-4√35)/(-4.9*2)=4,4555...(s)

t=(-20+4√35)/(-2*4.9)=-0,37391... to exclude (time must be >0)