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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 125 · 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 4 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 12 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  3. 3.🔺 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?
  4. 4.True or false: an igloo uses an arch. (a) False (b) True
  5. 5.🔺 Which strong shape does a bicycle frame use? (a) arch (b) beam (c) triangle (d) dome
  6. 6.🔺 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?
  7. 7.🔺 Which strong shape does a fort gateway use? (a) arch (b) dome (c) beam (d) triangle
  8. 8.True or false: a bicycle frame uses triangles. (a) True (b) False
  9. 9.Which of these uses a dome? (a) a roof truss (b) a shelf on two brackets (c) a truss bridge side (d) a round palace roof
  10. 10.🔺 Which strong shape does a crane arm use? (a) dome (b) triangle (c) arch (d) beam
  11. 11.🔺 A flat frame has 8 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
  12. 12.Which of these uses a beam? (a) a slab over a canal (b) a truss bridge side (c) a round palace roof (d) an igloo
  13. 13.🔺 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?
  14. 14.True or false: a fort gateway uses an arch. (a) False (b) True
  15. 15.True or false: an igloo uses a dome. (a) True (b) False
  16. 16.🔺 A flat frame has 11 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
  17. 17.Which of these uses triangles? (a) a fort gateway (b) a slab over a canal (c) a truss bridge side (d) a plank over a drain
  18. 18.🔺 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
  19. 19.True or false: an igloo uses triangles. (a) False (b) True
  20. 20.🔺 A frame shaped like a hexagon is made of straws joined by loose pins, with 1 corner-to-corner brace. Is it rigid or wobbly? (a) wobbly (b) rigid
  21. 21.🔺 Which strong shape does a shelf on two brackets use? (a) arch (b) dome (c) triangle (d) beam
  22. 22.🔺 Which shape keeps its shape best when its corners are pinned? (a) square (b) hexagon (c) rectangle (d) triangle
  23. 23.🔺 Which strong shape does a roof truss use? (a) arch (b) triangle (c) beam (d) dome
  24. 24.🔺 Which strong shape does a truss bridge side use? (a) arch (b) beam (c) triangle (d) dome
  25. 25.Which of these uses triangles? (a) an old stone bridge (b) an igloo (c) an electric pylon (d) a round palace roof
  26. 26.True or false: a truss bridge side uses an arch. (a) True (b) False
  27. 27.🔺 Why can an arch carry heavy loads? (a) it works in compression (b) it bends easily (c) it is very light (d) it is hollow
  28. 28.True or false: a planetarium roof uses a dome. (a) False (b) True
  29. 29.🔺 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?
  30. 30.🔺 Which strong shape does a slab over a canal use? (a) beam (b) arch (c) dome (d) triangle
  31. 31.🔺 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) wobbly (b) rigid
  32. 32.True or false: an electric pylon uses triangles. (a) True (b) False
  33. 33.🔺 How do engineers stop a square frame from wobbling? (a) add a diagonal brace (b) paint it (c) take off a side (d) make it bigger
  34. 34.🔺 A beam bends under a load. Its top side is … (a) floating (b) not affected (c) stretched (tension) (d) squeezed (compression)
  35. 35.Which of these uses an arch? (a) a shelf on two brackets (b) a slab over a canal (c) an old stone bridge (d) a bicycle frame
  36. 36.🔺 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?
  37. 37.🔺 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
  38. 38.Which of these uses triangles? (a) a fort gateway (b) a lintel over a door (c) a bicycle frame (d) a curved stone doorway
  39. 39.True or false: a crane arm uses a dome. (a) True (b) False
  40. 40.🔺 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?

Answer key

  1. 9
  2. 25
  3. 2
  4. False
  5. triangle
  6. 6
  7. arch
  8. True
  9. a round palace roof
  10. triangle
  11. 5
  12. a slab over a canal
  13. 15
  14. True
  15. True
  16. 8
  17. a truss bridge side
  18. rigid
  19. False
  20. wobbly
  21. beam
  22. triangle
  23. triangle
  24. triangle
  25. an electric pylon
  26. False
  27. it works in compression
  28. True
  29. 7
  30. beam
  31. wobbly
  32. True
  33. add a diagonal brace
  34. squeezed (compression)
  35. an old stone bridge
  36. 3
  37. rigid
  38. a bicycle frame
  39. False
  40. 27

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