Help Free fall, looking for time of motion off of a bridge.

[cassiek]

Help! Free fall, looking for time of motion off of a bridge.

Homework Statement

A person standing on a bridge throws a ball upward with an initial velocity of 23 m/s straight upwards so if it comes back down it will just pass the edge of the bridge and keep going down.
a) where will the ball be after 5.0s?
b) how long will it take to hit the water if the water 10m below the ball's release point?
c) what velocity will the ball have when it reaches the water?

Homework Equations

The kinematics equations of motion.

The Attempt at a Solution

for a) I used the equation Δd = vΔt + 1/2aΔt² (where d is displacement, v is the initial velocity, a is acceleration due to gravity, and t is the time) and I solved for d. I got -7.5 m. I'm hoping this is correct!
I don't know how to tackle b) and c) though, so advice is GREATLY APPRECIATED!

 

[supratim1]

when ball is going upwards, a = -g, and when it is coming downwards, a = g, g = 9.8 m/s^2

 

[supratim1]

and yes, Welcome to PF cassiek!

 

[ashishsinghal]

Help! Free fall, looking for time of motion off of a bridge.

Seems you were falling off the bridge.

Use the same equation for b part. This time you have displacement but not time.
use conservation of energy for the third part.