# Build a piece of equipment that can break the descent...

1. Jan 17, 2016

### our7thheaven

9th grade student is struggling trying to come up with a design that can meet the below requirement. Any help is appreciated.

1. The problem statement, all variables and given/known data

The purpose is to build a new piece of equipment that can break the descent of an object from a certain height. The object in this situation a metal marble will be dropped from a height of about 2.7m above the floor into the device built.

Device parameters: The marble acceleration is not greater than 9g's (90m/S squared)

You must determine where you plan to begin slowing the marble down and how much distance you plan to stop the marble in.

Marble cannot touch the floor or hit the floor though your device.
Materials are reusable
Must be built and tested in 1 class period.

The device will be tested 3 times. Will have 5 mins between tests to collect data and reset the device. The average of the 3 drops will be used to see how many G's are exerted on the marble.

Last edited: Jan 17, 2016
2. Jan 17, 2016

### Student100

You didn't really include how you plan on doing this? There are several interesting ways I can think of. Why don't you try to reason it out a bit more.

3. Jan 17, 2016

### our7thheaven

This is my first ever attempt at trying to come up with a strategy or plan to successfully complete the objective. I must say I was slightly disappointed that this was not a group assignment where we could brainstorm ideas and arrive at a group solution. Being solo here is causing me some anxiety because my attempts at using the Internet to research similar solutions have come up blank. I have not given up, but I am feeling my efforts so far have not been very rewarding.

4. Jan 17, 2016

### Student100

Stop with the Internet searches and think. What do imagine might work?

5. Jan 17, 2016

### our7thheaven

I envision have a clear tube that is 2.7m long and stuffing it with tissue near the bottom so that the descent can be stopped before it hits the floor. I just don't see how I can limit the descent to be no more than 9 G's.

I also thought about creating a ramp, but the requirement days "drop", so I abandoned that thought.

I also thought about connecting an elastic band to the marble, but that seems like a unrealistic setup because the marble is steel.

I find it hard to believe I can create something with stuff accessible to me in my house!?

Very disheartening. :(

6. Jan 17, 2016

### Student100

Why don't you first run through some back of the napkin calculations for g force the marble would undergo when it isn't stopped and collides with the floor. Next, look at how stopping it over a larger distance/time interval will affect how many g's the marble undergoes. Then you'll an idea of what kind of apparatus you're going to need to build.

The tissue idea can work, I don't know of all the constraints you have, but I'm assuming the purpose of this experiment is get you to think about designing experiments. Do some basic calculations, then get building. Trail and error are powerful tools. Set things up there and ... experiment. There are probably lots of different things you can find around the house to solve this problem. Just keep thinking.

Last edited: Jan 17, 2016
7. Jan 18, 2016

### CWatters

+1 to that. If you have covered the equation of motion ( constant acceleration) then you can estimate the minimum stopping distance below which it will break the g limit.

8. Jan 19, 2016

### our7thheaven

Thank you all for your support. Adding a sense of teamwork to the effort motivates me. This truly is the first "solo" project I have had. Up to this point, in all my other classes, projects were a team effort. You would think this being my first ever physics class, we might have come out of the gate with a group experience, followed by a solo effort. It's all good though. I expect they are trying to see who really "has it."