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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 651 · 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.🔺 A flat frame has 9 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
  2. 2.True or false: a bicycle frame uses an arch. (a) True (b) False
  3. 3.True or false: an old stone bridge uses an arch. (a) True (b) False
  4. 4.🔺 How do engineers stop a square frame from wobbling? (a) paint it (b) add a diagonal brace (c) take off a side (d) make it bigger
  5. 5.🔺 One side of a straw bridge is a row of 3 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  6. 6.True or false: a planetarium roof uses a dome. (a) True (b) False
  7. 7.🔺 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?
  8. 8.🔺 One side of a straw bridge is a row of 15 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  9. 9.🔺 A flat frame has 10 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
  10. 10.🔺 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?
  11. 11.True or false: a plank over a drain uses triangles. (a) True (b) False
  12. 12.🔺 One side of a straw bridge is a row of 2 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  13. 13.🔺 Which strong shape does a planetarium roof use? (a) dome (b) arch (c) beam (d) triangle
  14. 14.🔺 Which strong shape does a shelf on two brackets use? (a) arch (b) beam (c) triangle (d) dome
  15. 15.🔺 Which strong shape does an electric pylon use? (a) dome (b) arch (c) beam (d) triangle
  16. 16.🔺 Which strong shape does a fort gateway use? (a) dome (b) arch (c) triangle (d) beam
  17. 17.🔺 Which shape keeps its shape best when its corners are pinned? (a) hexagon (b) square (c) triangle (d) rectangle
  18. 18.True or false: a planetarium roof uses a beam. (a) True (b) False
  19. 19.Which of these uses triangles? (a) an old stone bridge (b) a planetarium roof (c) a truss bridge side (d) a slab over a canal
  20. 20.🔺 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?
  21. 21.🔺 Which strong shape does a crane arm use? (a) triangle (b) arch (c) beam (d) dome
  22. 22.Which of these uses a dome? (a) a slab over a canal (b) a plank over a drain (c) a planetarium roof (d) a truss bridge side
  23. 23.🔺 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?
  24. 24.True or false: a curved stone doorway uses a dome. (a) False (b) True
  25. 25.Which of these uses triangles? (a) a crane arm (b) a curved stone doorway (c) an igloo (d) a planetarium roof
  26. 26.Which of these uses a beam? (a) an old stone bridge (b) a lintel over a door (c) a planetarium roof (d) a round palace roof
  27. 27.🔺 Which strong shape does a lintel over a door use? (a) dome (b) arch (c) triangle (d) beam
  28. 28.🔺 Which strong shape does a plank over a drain use? (a) triangle (b) beam (c) dome (d) arch
  29. 29.🔺 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?
  30. 30.True or false: a plank over a drain uses an arch. (a) False (b) True
  31. 31.🔺 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
  32. 32.🔺 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?
  33. 33.True or false: a crane arm uses an arch. (a) False (b) True
  34. 34.Which of these uses a beam? (a) a fort gateway (b) an old stone bridge (c) a bicycle frame (d) a shelf on two brackets
  35. 35.🔺 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?
  36. 36.🔺 Why can an arch carry heavy loads? (a) it is very light (b) it bends easily (c) it is hollow (d) it works in compression
  37. 37.🔺 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?
  38. 38.🔺 Which strong shape does a slab over a canal use? (a) arch (b) triangle (c) dome (d) beam
  39. 39.Which of these uses an arch? (a) a round palace roof (b) a bicycle frame (c) an old stone bridge (d) a slab over a canal
  40. 40.🔺 Which strong shape does a round palace roof use? (a) beam (b) arch (c) triangle (d) dome

Answer key

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

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