Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    Hi,
    please take your time to read this

    Im currently doing pile driving for me A2 physics coursework. And i need you guys to help me on what to do next.

    This is my experiment set-up and what i've done so far:

    -heavy steel rod
    -glass tube to guide steel rod
    -nail
    -plasterthene or playdo as the material for the nail to hit through
    -ruler

    What i do is that i use the steel rod to impact the nail into the playdo, and take measurements from different heights that i lift the rod and the depth of nail goes down

    And here are my problems:

    im pretty much stuck after doing this. I'm not sure how i can improve the experiment so i get a more accurate reading etc. What to experiment next? Should i use a different material? or a heavier steel rod? I dont see what to do next :eek3:

    Also i think that the resistance of the playdo that acts on the nail is not affected by the depth, and it would become somewhat constant after a certain depth?

    And what are the important safety issues of this experiment? There are always some but i dont see any of them here :confused:

    ANY reasonable suggestions are GREATLY APPRECIATED!!

    Thanks a lot guys
    Offline

    6
    ReputationRep:
    if safety isn't an issue then just say it isnt. It doesnt have to be..

    some ideas;

    hit the same nail repeatedly - does it always go down the same amount

    try changing the temp of the plasticine (e.g. put it in the fridge or in a water bath). What difference does that make?

    make some plasticine with different coloured layers. After it has been hit cut out a cross section to see how it has been stressed internally

    try filming an impact. what can you learn from the replay?

    try different sized nails. Try filing their ends different shapes.

    try driving it in at an angle
    Offline

    8
    ReputationRep:
    (Original post by Concretepoo)
    Hi,
    please take your time to read this

    Im currently doing pile driving for me A2 physics coursework. And i need you guys to help me on what to do next.

    This is my experiment set-up and what i've done so far:

    -heavy steel rod
    -glass tube to guide steel rod
    -nail
    -plasterthene or playdo as the material for the nail to hit through
    -ruler

    What i do is that i use the steel rod to impact the nail into the playdo, and take measurements from different heights that i lift the rod and the depth of nail goes down

    And here are my problems:

    im pretty much stuck after doing this. I'm not sure how i can improve the experiment so i get a more accurate reading etc. What to experiment next? Should i use a different material? or a heavier steel rod? I dont see what to do next :eek3:

    Also i think that the resistance of the playdo that acts on the nail is not affected by the depth, and it would become somewhat constant after a certain depth?

    And what are the important safety issues of this experiment? There are always some but i dont see any of them here :confused:

    ANY reasonable suggestions are GREATLY APPRECIATED!!

    Thanks a lot guys
    Most interesting thing I can think of is this - vary the surface area of the nail tip so you can investigate how this affects the penetration depth of the nail. You could either get thicker and thinner nails, ideally of the same mass if possible, or fix a series of different sized thin flat sheets of plastic onto the end of the existing nail, effectively adding very little to its mass but changing the surface area of the tip hugely.

    While you do this drop the rod from the same height each time. This means the force that the nail is exerting on the playdo is constant. Most probably you'll just confirm that pressure = force/area, but hey it's a result!

    Another option is testing your own hypothesis:

    i think that the resistance of the playdo that acts on the nail is not affected by the depth, and it would become somewhat constant after a certain depth?
    Make the playdo thicker and thicker whilst dropping the rod from the same height. You could plot playdo thickness against nail penetration depth to see if there is any link?

    Finally you could vary temperature - heat/cool the playdo (if you can get your hands on some liquid nitorgen that could be fun ) and see if that affects the penetration depth (my guess is it very much will!). Again drop the rod from the same height.

    Safety - say stuff like 'make sure rod doesn't fall off course and shatter guiding tube' and 'make sure playdo is mounted on something to stop the nail poking out the other side' etc. Basically think of how anything that is sharp/can break/moves fast/is heavy could get out of control.

    As for accuracy improvements, not really much that would seem to make a huge difference in this experiment...

    Those are my thoughts!
    Offline

    8
    ReputationRep:
    For extra fun, try different methods of moulding.
    You can try just pressing it into a lump, or stretch it out and fold it.....
    Offline

    10
    You need a hypothesis to test.
    What is the physics behind what you are doing? Can you suggest a formula or possible relationship which can be confirmed by experimental results?
    From what you are doing, it looks like you could talk about energy.
    On the one hand you have the steel rod raised to a height h, with resulting potential energy mgh where m is its mass.
    On the other hand you have the nail penetrating the soft material to a depth x. If F is the average force of the nail on the material, then the work done is Fx.
    You could speculate that, for example, Fx=mgh and test this by drawing a graph of, say, x against h, keeping m constant.
    You could further test this hypothesis by changing the mass of the rod and plotting x against m, keeping h constant.
    You may find that there is a direct proportionality, but only for a limited range of x.
    The problem is that the value of F is somewhat unknown. It depends on the shape of the end of the nail and the pressure exerted. (P=F/A) as well as the softness of the material.
    So using a sharper nail gives a smaller A; and F=PA.
    You need to keep all the other variables constant, and just vary the two you are interested in.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 9, 2010

University open days

  1. University of Cambridge
    Christ's College Undergraduate
    Wed, 26 Sep '18
  2. Norwich University of the Arts
    Undergraduate Open Days Undergraduate
    Fri, 28 Sep '18
  3. Edge Hill University
    Faculty of Health and Social Care Undergraduate
    Sat, 29 Sep '18
Poll
Which accompaniment is best?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.