A ball is kicked horizontally off a cliff 40m high. After 3seconds, the person that is on top of the cliff hears the thump of the ball hitting the floor. Assuming speed of sound travles 343m/s in air, what is the initial velocity that the ball was kicked at?(adsbygoogle = window.adsbygoogle || []).push({});

Please check if I did it correct....

Find time it takes for the ball to hit the floor:

d=.5at^2

40m=.5(9.8)(t^2)

t=2.857142857 s

Find time it takes for the sound to travel back to person on cliff:

3-2.857142857=.1428571429

Find the distance away from cliff:

d=vt

d=343*.1428571429

d=49

Find the distance travled in the x-direction:

49^2=40^2+x^2

x=28.3019434m

Find the initial speed:

v=d/t

v=28.3019434m/2.857142857s

v=9.9m/s

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Finding inital velocity

**Physics Forums | Science Articles, Homework Help, Discussion**