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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 276 · 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 13 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  2. 2.Which of these uses a beam? (a) a slab over a canal (b) an electric pylon (c) a planetarium roof (d) a crane arm
  3. 3.Which of these uses triangles? (a) a shelf on two brackets (b) a plank over a drain (c) a crane arm (d) a planetarium roof
  4. 4.🔺 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) rigid (b) wobbly
  5. 5.🔺 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
  6. 6.🔺 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?
  7. 7.🔺 Which strong shape does an igloo use? (a) triangle (b) arch (c) beam (d) dome
  8. 8.True or false: a roof truss uses an arch. (a) False (b) True
  9. 9.True or false: a shelf on two brackets uses a beam. (a) False (b) True
  10. 10.🔺 Why can an arch carry heavy loads? (a) it bends easily (b) it is very light (c) it is hollow (d) it works in compression
  11. 11.Which of these uses triangles? (a) a curved stone doorway (b) a lintel over a door (c) a truss bridge side (d) a fort gateway
  12. 12.🔺 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?
  13. 13.🔺 Which strong shape does an old stone bridge use? (a) triangle (b) dome (c) beam (d) arch
  14. 14.🔺 A frame shaped like a square is made of straws joined by loose pins, with 0 corner-to-corner braces. Is it rigid or wobbly? (a) rigid (b) wobbly
  15. 15.🔺 How do engineers stop a square frame from wobbling? (a) paint it (b) take off a side (c) make it bigger (d) add a diagonal brace
  16. 16.True or false: a lintel over a door uses a dome. (a) False (b) True
  17. 17.🔺 Which strong shape does a bicycle frame use? (a) triangle (b) beam (c) dome (d) arch
  18. 18.🔺 Which strong shape does a round palace roof use? (a) dome (b) triangle (c) beam (d) arch
  19. 19.True or false: a slab over a canal uses a beam. (a) False (b) True
  20. 20.True or false: an old stone bridge uses an arch. (a) False (b) True
  21. 21.🔺 Which strong shape does a slab over a canal use? (a) beam (b) triangle (c) dome (d) arch
  22. 22.🔺 Which strong shape does a roof truss use? (a) dome (b) beam (c) triangle (d) arch
  23. 23.🔺 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?
  24. 24.🔺 Which shape keeps its shape best when its corners are pinned? (a) hexagon (b) triangle (c) square (d) rectangle
  25. 25.🔺 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?
  26. 26.True or false: a crane arm uses a dome. (a) True (b) False
  27. 27.🔺 Which strong shape does a crane arm use? (a) arch (b) beam (c) triangle (d) dome
  28. 28.True or false: an electric pylon uses an arch. (a) True (b) False
  29. 29.Which of these uses triangles? (a) an old stone bridge (b) a roof truss (c) a fort gateway (d) a shelf on two brackets
  30. 30.🔺 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?
  31. 31.🔺 A frame shaped like a hexagon is made of straws joined by loose pins, with 3 corner-to-corner braces. Is it rigid or wobbly? (a) wobbly (b) rigid
  32. 32.🔺 Which strong shape does an electric pylon use? (a) beam (b) arch (c) dome (d) triangle
  33. 33.🔺 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) rigid (b) wobbly
  34. 34.Which of these uses a dome? (a) an igloo (b) a plank over a drain (c) a fort gateway (d) a lintel over a door
  35. 35.Which of these uses an arch? (a) a curved stone doorway (b) a plank over a drain (c) a bicycle frame (d) a shelf on two brackets
  36. 36.🔺 One side of a straw bridge is a row of 6 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  37. 37.🔺 Which strong shape does a shelf on two brackets use? (a) beam (b) triangle (c) dome (d) arch
  38. 38.True or false: a plank over a drain uses a beam. (a) False (b) True
  39. 39.True or false: a shelf on two brackets uses triangles. (a) True (b) False
  40. 40.🔺 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?

Answer key

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

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