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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 130 · 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.Which of these uses triangles? (a) an old stone bridge (b) a bicycle frame (c) a planetarium roof (d) a shelf on two brackets
  2. 2.🔺 Why can an arch carry heavy loads? (a) it bends easily (b) it is hollow (c) it is very light (d) it works in compression
  3. 3.🔺 A beam bends under a load. Its top side is … (a) stretched (tension) (b) not affected (c) floating (d) squeezed (compression)
  4. 4.🔺 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?
  5. 5.Which of these uses a dome? (a) a roof truss (b) a truss bridge side (c) a planetarium roof (d) a bicycle frame
  6. 6.🔺 Which shape keeps its shape best when its corners are pinned? (a) triangle (b) rectangle (c) square (d) hexagon
  7. 7.🔺 Which strong shape does a lintel over a door use? (a) arch (b) beam (c) dome (d) triangle
  8. 8.🔺 Which strong shape does an electric pylon use? (a) arch (b) beam (c) dome (d) triangle
  9. 9.True or false: a lintel over a door uses a dome. (a) True (b) False
  10. 10.🔺 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?
  11. 11.True or false: an igloo uses a dome. (a) False (b) True
  12. 12.🔺 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) wobbly (b) rigid
  13. 13.🔺 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) rigid (b) wobbly
  14. 14.True or false: a curved stone doorway uses a dome. (a) True (b) False
  15. 15.🔺 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?
  16. 16.🔺 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?
  17. 17.🔺 How do engineers stop a square frame from wobbling? (a) add a diagonal brace (b) make it bigger (c) paint it (d) take off a side
  18. 18.🔺 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?
  19. 19.🔺 Which strong shape does an igloo use? (a) beam (b) dome (c) arch (d) triangle
  20. 20.🔺 Which strong shape does a roof truss use? (a) dome (b) beam (c) arch (d) triangle
  21. 21.🔺 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?
  22. 22.True or false: an igloo uses triangles. (a) False (b) True
  23. 23.Which of these uses triangles? (a) a lintel over a door (b) a curved stone doorway (c) an electric pylon (d) an igloo
  24. 24.🔺 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?
  25. 25.🔺 Which strong shape does a truss bridge side use? (a) beam (b) triangle (c) arch (d) dome
  26. 26.True or false: a crane arm uses triangles. (a) True (b) False
  27. 27.🔺 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
  28. 28.Which of these uses an arch? (a) a slab over a canal (b) a curved stone doorway (c) a lintel over a door (d) a truss bridge side
  29. 29.Which of these uses a beam? (a) an electric pylon (b) a slab over a canal (c) a truss bridge side (d) an igloo
  30. 30.🔺 A frame shaped like a square is made of straws joined by loose pins, with 1 corner-to-corner brace. Is it rigid or wobbly? (a) rigid (b) wobbly
  31. 31.Which of these uses triangles? (a) a crane arm (b) a lintel over a door (c) a round palace roof (d) a fort gateway
  32. 32.Which of these uses a dome? (a) a plank over a drain (b) a roof truss (c) a truss bridge side (d) an igloo
  33. 33.True or false: a round palace roof uses an arch. (a) True (b) False
  34. 34.🔺 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?
  35. 35.True or false: an electric pylon uses triangles. (a) True (b) False
  36. 36.🔺 Which strong shape does a planetarium roof use? (a) beam (b) arch (c) triangle (d) dome
  37. 37.True or false: a crane arm uses a dome. (a) True (b) False
  38. 38.True or false: a roof truss uses triangles. (a) False (b) True
  39. 39.Which of these uses triangles? (a) a fort gateway (b) a round palace roof (c) an igloo (d) a roof truss
  40. 40.Which of these uses an arch? (a) a slab over a canal (b) an old stone bridge (c) a crane arm (d) a roof truss

Answer key

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

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