# B Impact force on falling egg?

1. Sep 22, 2016

### houlahound

I searched engineering calculators and they rely on the input you know the stopping time or the stopping distance - easy for a car but not an egg.

Knowing either of these quantities makes the problem trivial, but how to estimate or calculate them??

What is the best assumption for either and how is the assumption justified for a free falling egg hitting concrete.

I would like to do it theoretically and not use video or force sensors.

Is this possible?

Last edited: Sep 22, 2016
2. Sep 22, 2016

### phinds

If you can't solve a problem without a calculator you should not expect to be able to solve it WITH a calculator.

3. Sep 22, 2016

### houlahound

Actually I just looked at how the calculator solved the problem ie what equations. I get the physics given impact time or distance - I have no idea how to get values for time or distance of stopping apart from measurement.

If you can point me in right direction be appreciated.

4. Sep 22, 2016

### phinds

Is that single word response supposed to mean something?

5. Sep 22, 2016

### houlahound

I have to post a random string then use the edit box to make the text not gibberish...tedious.

6. Sep 22, 2016

### phinds

That seems odd. How can you be able to post a string of gibberish but not instead post a real response?

7. Sep 22, 2016

### houlahound

Don't know....but back to the question.

8. Sep 23, 2016

### davenn

you have to make some effort yourself.....
list the things you know about the egg and its fall
then you can figure out how to find the force that the egg hits the ground with

9. Sep 23, 2016

### houlahound

Because a car a crushing distance is easy to estimate eg the crumple distance. Usually qouted around 0.5m.

An egg??

10. Sep 23, 2016

### davenn

forget about the crumple distance at this stage ... lets initially treat it as a solid object

again ...

Dave

11. Sep 23, 2016

### houlahound

Lands at speed root(2gh)
Above some height h egg cracks on impact.
No observable deformation, just catastrophic fracture.

Nothing else I can think of.

12. Sep 23, 2016

### davenn

you haven't stated any of the things that need to be considered to work out the force of the impact

here's some hints
mass of the egg,
height dropped from
acceleration rate at the time of impact

what is the formula for working out force of a falling object "in" gravity ?

Dave

Last edited: Sep 23, 2016
13. Sep 23, 2016

### houlahound

All I got from that is;

F=mass of egg x acceleration = mass of egg x velocity / time

Initial acceleration = g

velocity initial = root(2gh)

velocity final = 0

time from when egg hits ground until it stops moving ie collision duration I don't know and what needs to be known to work out impact force.

14. Sep 23, 2016

### davenn

try this .....

Impact Force from a Falling Object
The dynamic energy in a falling object at the impact moment when hitting the ground can be calculated as

E = Fw h
= m g h (4)

where

Fw = force due to gravity - weight (N, lbf)

g = acceleration of gravity (9.81 m/s2, 32.17405 ft/s2)

h = falling height (m)

The equation can be combined with the equation of work to:

F = m g h / s

now using that work out the force