Question

Suppose a young child throws a tennis ball into the air as hard as he can. Which of the following is the most reasonable solution for the time it takes the ball to land?
A- (6 seconds)
B- (1.1 seconds)
C- (−2 seconds)
D- (10 seconds)

Answer 1

How high can a little kid throw it? Maybe thirty feet (10 meters) ?
potential energy at top = m g H
kinetic energy at throw = (1/2 ) m Vi^2
so 2 g H = Vi^2
H = Vi^2 / 2 g
g is about 10 m/s^2
H = Vi^2 / 20 = 10 meters
so Vi^2 = 200
Vi = about 14 m/s at the throw
v = Vi - g t = 14 - 10 t
at top v = 0 so about 1.4 seconds to get up to H
then 1.4 seconds to fall
so I think about 3 seconds

Answer 2

the issue is that is not one of the answer choices

Answer 3

ok nevermind it was 1.1

Answer 4

tiny kid :)