How Tension and Compression Makes Wood Stronger

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How Tension and Compression Makes Wood Stronger
Science Project
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Purpose

• The purpose of this experiment is to demonstrate
  how compression makes wood stronger.

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Hypothesis

• I think that at first, when the weight is added,
  the wood will snap. Then when it is compressed
  enough, it will be able to hold the weight.
  Eventually it will get too compressed, and snap
  off. I think this will happen because the wood
  will buckle up too much and break without any
  weight.

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Materials

• Pine wood-Turn Buckle-Eye hooks
  (2)-String-Rabbit Wire-Nails-5lb weight

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Method

• 1.Construct a frame to compress wood.2.Get a
  piece of pine wood and cut it in 12 equal
  pieces3.Put one piece of wood in the frame
  horizontally (measuring 19 ½ inches)4.hang
  a 5lb weight on to wood (using a bent nail for
  hook, and tied to string)5.Record if wood can
  hold weight6.Take out piece of wood and put
  another in7.Tighten turn buckle ½ inch so that
  the wood bends up (cause compression)8. record
  if wood can hold weight9. repeat steps 6-8 two
  more times, (make sure buckle is turned so that
  more compression is caused each time)

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Variables

• Manipulated- how much wood is compressed each
  timeResponding- which amount of compression
  causes wood to be strongerControlled- The type
  of wood, the size of wood, the wood frame used,
  the amount of weight used each time

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Results
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19 ½ inches apart
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19 inches apart
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18 ½ inches apart
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18 inches apart
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Conclusions

• In conclusion I found out that wood is stronger
  when it is compressed. But if you use too much
  compression the wood gets weaker. When wood is
  compressed it bends upwards, and gets tighter
  which makes it stronger. If you push down on it
  with your finger you can see that it is much
  stronger compressed then it is when it is not
  compressed.

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Result Conclusions..

• - When the wood was flat (19 ½ inches between
  frames posts) it had no compression and it
  snapped when the weight was added.- When the
  wood was slightly compressed and when the weight
  was added it sagged down before snapping. There
  was 19 inches between the 2 posts- When there
  was 18 ½ inches between the 2 posts there was
  more compression, so the wood held the weight
  with no problem- When the wood was bent right
  up and there was only 18 inches between the 2
  posts, the wood snapped right away due to too
  much compression. This shows that my hypothesis
  was correct

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Sources of Error

• Here are some ways I could of got incorrect
  results 1.Some pieces of wood could have been
  slightly stronger than others. 2.The ides on the
  wood frame might have been too high and floppy,
  so it would be harder to get the right amount of
  compression 3.there could have been too much
  compression used

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Ways to Improve

• Here are some things I could of done to make my
  experiment better 1. I could of stress- tested
  the wood to make sure each piece was exactly the
  same.
• 2. I could of used a harder type of wood. (Ex.
  Birch, or Oak)
• 3. The sides on the frame could of been made
  shorter, so it would be more stable and easier to
  add the compression.