Mrs. Kubb 6th Grade October 6, 2011 What will best holds two pieces of pine together, a screw or a nail? Hypothesis: My hypothesis is that a screw will hold two pieces of pine together better than a nail. Materials : 3, 1½ inch wood screws 3, 1½ inch nails 2 pieces of 2 x 4 scrap pine (about the same length) Claw Hammer Screwdriver 3 pound sledge hammer Vice Ruler Safety: 1) Wear safety goggles. I wore safety goggles to protect my eyes when I sawed the wood and used the hammer. 2)Clean work space. I made sure that the work space was clean so that no injuries would occur. Such as stepping on a nail. Procedure: 1) Saw 1, 2x4 into 6 equal parts 2) Screw 3 of the 6 cut boards on the 2 inch side of the other 2 x 4 3) Nail the other 3 cut boards on the 2 inch side of the other 2 x 4 4) Number the pieces 1-3 for the nails and for the screws Procedure continued: 5) Put the opposite side of the board into a vice. Tighten the vice to hold the board steady. 6) Hold the sledge hammer with two hands and let the head of the hammer drop towards nail 1. Let the hammer drop 5 times. 7) Using the ruler measure the distance between nail board 1 and the 2 x 4 block. 8) Repeat steps 6 and 7 for Nails 2 and 3 and for screws 1-3. Variables: Independent variables: Nails/screws Controlled variables: pine wood 3 pound sledge number of hits Data Collection: Trial 1 2 3 Screw Distance (mm) 0 mm (loosened enough to wiggly the board) 2 mm 0 mm (loosened enough to wiggly the board) Nail Distance (mm) Completely off (45 mm) Completely off (45 mm) 22 mm I estimated that a 1 ½ in nail and screw was about 3.8 cm in length. Given the wood width I am saying that a board that fell off went a total distance of 4.5 cm (45 mm). Data Analysis: Screw and Nail Test 45 Distance in mm 40 35 30 Trial 1 Trial 2 Trial 3 25 20 15 10 5 0 Screws Nails Conclusion: In conclusion, my hypothesis stated that screws would hold pine together better than nails. My hypothesis was correct. According to the data screws held the boards together because the largest distance was 2 mm. The nails did not keep the 2 pieces of wood together, instead the wood fell off. Possible problems that may have occurred during the lab were that the amount of force delivered by the hammer may not of been the same for each trial. Another problem was hitting each board on the same spot. Possible solution for the amount of force would be to set weights on the overhang part of the board and see how much weight each would hold.