# Impact force from a falling object

#### iccdan

I used some formulas to determine the impact force of a bubble wrapped 1kg object dropped 1 meter and traveling .03m after impact. But I need some help with the next part. What if an identical bubble wrapped 1kg object is placed on top and both are dropped at the same time? Will the wrapping between the two objects cause the top object to feel the same impact force? Will the bottom object feel more impact force or does the wrapping between them eliminate any influence from the top object? Thanks!

Related Other Physics Topics News on Phys.org

Gold Member
Hi
Which formulas?

#### iccdan

Sophie,
I appreciate the quick response. I used these formulas: velocity(m/s) = √2gh, kinetic energy(joules) = 1/2(mv²), impact force(Newtons) = joules/distance traveled after impact, equivalent G-force = Newtons/(kg*gravity). I also cheated and used the calculator at this Georgia State U website: http://hyperphysics.phy-astr.gsu.edu/hbase/flobi.html

Thanks

#### sophiecentaur

Gold Member
I think you have chosen a very difficult problem to solve here. You may be better to consider the case of two masses connected by springs, with a second spring between the first mass and the wall. Then the second mass would only be experiencing forces from the first mass during the impact. That would boil down to a fairly straightforward 'waves on a short transmission line' problem.

#### iccdan

Ok, now you are way over my head. Where can I get info to learn about 'waves on a short transmission line'?

#### sophiecentaur

Gold Member
Sorry. But you could appreciate that two masses and two springs could be a simpler problem than your original one.
It's a matter of writing an equation to describe the situation and then solving it. Easy if you say it quickly! Haha
It's the basics of all wave transmission theory.

#### sophiecentaur

Gold Member
http://www.ph.biu.ac.il/~rapaport/java-apps/spring.html" [Broken] is an animation which will give you an idea of what I'm describing. You can build a system of two springs and three masses in a line (not what you actually wanted but it's a start) and you can see what happens to the mass at one end when you twitch the mass at the other end.
You can extend this to what happens when one mass happens to be huge (a wall).
Have a look ands see if it helps.

Last edited by a moderator:

#### iccdan

Sophie,
Thanks for the link. I went to it and played with the mass and springs which gave me a better understanding of the physics involved. I also sent an email to the creator of the site to see if he would be able to add gravity to it. That would really be a help!

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving