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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 606 · 40 questions
TalentJR

Engineer's tip (Triangles stay put): Triangles are rigid; trusses, towers and frames use them. A pin-jointed frame with n sides needs n − 3 corner-to-corner braces; a row of n triangles uses 2n + 1 straws. Arches squeeze (compression); beams span gaps; domes are arches turned round in a circle.

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  1. 1.🔺 One side of a straw bridge is a row of 7 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  2. 2.🔺 One side of a straw bridge is a row of 11 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  3. 3.🔺 One side of a straw bridge is a row of 10 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  4. 4.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) triangle (c) hexagon (d) square
  5. 5.True or false: a bicycle frame uses triangles. (a) False (b) True
  6. 6.🔺 A frame shaped like a pentagon is made of straws joined by loose pins, with 0 corner-to-corner braces. Is it rigid or wobbly? (a) rigid (b) wobbly
  7. 7.🔺 Which strong shape does a slab over a canal use? (a) beam (b) triangle (c) arch (d) dome
  8. 8.True or false: a slab over a canal uses a beam. (a) True (b) False
  9. 9.🔺 Which strong shape does an electric pylon use? (a) triangle (b) dome (c) beam (d) arch
  10. 10.🔺 A frame shaped like a pentagon is made of straws joined by loose pins, with 2 corner-to-corner braces. Is it rigid or wobbly? (a) wobbly (b) rigid
  11. 11.🔺 A frame shaped like a triangle is made of straws joined by loose pins, with 0 corner-to-corner braces. Is it rigid or wobbly? (a) wobbly (b) rigid
  12. 12.🔺 One side of a straw bridge is a row of 13 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  13. 13.🔺 One side of a straw bridge is a row of 9 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  14. 14.Which of these uses a beam? (a) an old stone bridge (b) an electric pylon (c) a round palace roof (d) a slab over a canal
  15. 15.True or false: a fort gateway uses an arch. (a) False (b) True
  16. 16.🔺 Which strong shape does a roof truss use? (a) arch (b) beam (c) dome (d) triangle
  17. 17.🔺 A flat frame has 12 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
  18. 18.True or false: an electric pylon uses a dome. (a) False (b) True
  19. 19.🔺 Why can an arch carry heavy loads? (a) it bends easily (b) it is very light (c) it works in compression (d) it is hollow
  20. 20.True or false: a roof truss uses triangles. (a) False (b) True
  21. 21.🔺 Which strong shape does a shelf on two brackets use? (a) arch (b) triangle (c) dome (d) beam
  22. 22.🔺 One side of a straw bridge is a row of 5 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  23. 23.🔺 One side of a straw bridge is a row of 4 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  24. 24.🔺 Which strong shape does a planetarium roof use? (a) arch (b) beam (c) triangle (d) dome
  25. 25.Which of these uses a beam? (a) an electric pylon (b) a curved stone doorway (c) an old stone bridge (d) a lintel over a door
  26. 26.True or false: an electric pylon uses triangles. (a) True (b) False
  27. 27.🔺 A flat frame has 6 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
  28. 28.🔺 Which strong shape does a lintel over a door use? (a) beam (b) dome (c) triangle (d) arch
  29. 29.True or false: a shelf on two brackets uses a dome. (a) False (b) True
  30. 30.🔺 A flat frame has 7 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
  31. 31.🔺 A frame shaped like a hexagon is made of straws joined by loose pins, with 0 corner-to-corner braces. Is it rigid or wobbly? (a) wobbly (b) rigid
  32. 32.True or false: an igloo uses a dome. (a) False (b) True
  33. 33.Which of these uses triangles? (a) a round palace roof (b) a slab over a canal (c) a curved stone doorway (d) a truss bridge side
  34. 34.🔺 A flat frame has 5 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
  35. 35.Which of these uses a beam? (a) a shelf on two brackets (b) an old stone bridge (c) a truss bridge side (d) an electric pylon
  36. 36.🔺 Which strong shape does a fort gateway use? (a) dome (b) arch (c) beam (d) triangle
  37. 37.True or false: a curved stone doorway uses an arch. (a) False (b) True
  38. 38.🔺 One side of a straw bridge is a row of 12 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  39. 39.True or false: a truss bridge side uses a dome. (a) True (b) False
  40. 40.🔺 A flat frame has 4 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?

Answer key

  1. 15
  2. 23
  3. 21
  4. triangle
  5. True
  6. wobbly
  7. beam
  8. True
  9. triangle
  10. rigid
  11. rigid
  12. 27
  13. 19
  14. a slab over a canal
  15. True
  16. triangle
  17. 9
  18. False
  19. it works in compression
  20. True
  21. beam
  22. 11
  23. 9
  24. dome
  25. a lintel over a door
  26. True
  27. 3
  28. beam
  29. False
  30. 4
  31. wobbly
  32. True
  33. a truss bridge side
  34. 2
  35. a shelf on two brackets
  36. arch
  37. True
  38. 25
  39. False
  40. 1

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