Item 10 Madison hits a tennis ball with an initial velocity of 18 m/s straight up into the air. When she hits the ball, it is 1.2 m above the ground. Which equation can be used to find the time, t, it takes for the ball to reach the ground?

Let, t

a

and t

b

be the time of ascent and time of descend respectively.

Given, t

a

+t

d

=8

and t

a

=t

d

∴2t

a

=8

t

a

=4=t

d

From first equation of motion, v

2

=u

2

+g×t

d

v

2

=0+10×4

=40ms

−1

From second equation of motion, h=

2g

v

2

2

−u

2

2

=

2×10

160−0

=80m

answer: 5

step-by-step explanation: