Question

A ball dropped from a bridge takes 3.0 seconds to reach the water below. How far is the bridge above water?

PLEASE SHOW WORK. THANK YOU !

Answer 1

So what do you know is the equation for position of an object?

\[x_f=x_i + v_i t +\frac{ 1 }{ 2 }a t^2\]

So let's look at what we have in there,

final position
initial position
initial velocity
time
acceleration

What out of that do we know? What are we trying to figure out. Remember, if it was dropped, that means they didn't throw it. So what should the initial velocity be?

The final and initial positions should correspond to the height of the bridge, right? Think about it a little.

Answer 2

I don't know how to solve it.

Answer 3

what is it that you dont understand? @brandonhssm

Answer 4

@brandonhssm Think about it, and actually try without giving up. I'm helping you out here.

Answer 5

@ichiro how to solve it

Answer 6

If you can figure out those values that I listed, then you can plug them into that equation. Let's take it one step at a time.

What's the acceleration?

Answer 7

@Kainui I don't know

Answer 8

What direction do things fall when you let go of them?

Answer 9

Up, right?

Answer 10

@brandonhssm, a ball is dropped from height downward so what kind of acceleration will be there?

Answer 11

earth attracts every object, then?

Answer 12

I don't know

Answer 13

use your mind, it will be acceleration due to gravity which is denoted by small g. you know its value?

Answer 14

is it in the question?

Answer 15

brandon what do you want out of life?

Answer 16

yeah, they said the ball is dropped from height. they will not just tell you everything clearly. you have to read the question carefully and deduct what information they have given.

Answer 17

@Kainui what does that have to do with the question?

Answer 18

start over.
they said ball is dropped from height.
then ball must be in rest when they dropped, because something must be holding it.
it took three second for ball to touch the water.

Answer 19

what information do you get from this?

Answer 20

final velocity, initial velocity, time, acceleration, etc. see them in question and tell me?

Answer 21

@brandonhssm

Answer 22

time

Answer 23

tell me their values as well!

Answer 24

time = ?

Answer 25

3 secs

Answer 26

Good job.

Answer 27

wut else? they told you ball was at rest when they began, so intial velocity = ?

Answer 28

umm