Leaping Off the 400-Year-Old Bridge in Bosnia

[mandy9008]

Homework Statement

In Bosnia, the ultimate test of a young man's courage used to be to jump off a 400 year old bridge (now destroyed) into the River Neretva, 23 m below the bridge. (a) How long did the jump last? (b) How fast was the jumper traveling upon impact with the river?
(c) If the speed of sound in air is 341 m/s, how long after the jumper took off did a spectator on the bridge hear the splash?

Homework Equations

a. and b. change in Y=Voy t - .5 gt²

The Attempt at a Solution

a. v=21.23 m/s
b. t=2.167s
c. Vy=Voy - gt
341 m/s =21.23 m/s - 9.8 m/s² t
t=-32.63s
I know that time cannot be negative, but I have tried the inverse of this number also, and I am still getting it wrong. Am I even using the correct equation?

 

[Doc Al]

a. v=21.23 m/s
b. t=2.167s

OK.

c. Vy=Voy - gt
341 m/s =21.23 m/s - 9.8 m/s² t
t=-32.63s
I know that time cannot be negative, but I have tried the inverse of this number also, and I am still getting it wrong. Am I even using the correct equation?

No, you are not. The sound travels through the air at a constant speed. (The sound is not a projectile.)

 

[mandy9008]

Could you point me in the right direction as to the equation I am supposed to use?

 

[Doc Al]

Could you point me in the right direction as to the equation I am supposed to use?

What equation relates speed, distance, and time for something moving at constant speed? That's what you'll need to find the time it takes for the sound of the splash to travel up to the bridge.

(To find the total time, don't forget to add in the time it takes for the man to fall, which you've already calculated.)