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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 131 · 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 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
  2. 2.🔺 Which shape keeps its shape best when its corners are pinned? (a) triangle (b) rectangle (c) hexagon (d) square
  3. 3.🔺 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?
  4. 4.True or false: a roof truss uses an arch. (a) True (b) False
  5. 5.Which of these uses a dome? (a) a lintel over a door (b) a roof truss (c) a round palace roof (d) an electric pylon
  6. 6.🔺 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) rigid (b) wobbly
  7. 7.🔺 How do engineers stop a square frame from wobbling? (a) take off a side (b) make it bigger (c) add a diagonal brace (d) paint it
  8. 8.🔺 Which strong shape does a slab over a canal use? (a) beam (b) arch (c) triangle (d) dome
  9. 9.🔺 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?
  10. 10.🔺 Which strong shape does a plank over a drain use? (a) beam (b) triangle (c) arch (d) dome
  11. 11.Which of these uses a beam? (a) a slab over a canal (b) a planetarium roof (c) a crane arm (d) a truss bridge side
  12. 12.🔺 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?
  13. 13.🔺 Which strong shape does a lintel over a door use? (a) dome (b) arch (c) beam (d) triangle
  14. 14.True or false: an old stone bridge uses a dome. (a) False (b) True
  15. 15.🔺 A frame shaped like a pentagon is made of straws joined by loose pins, with 1 corner-to-corner brace. Is it rigid or wobbly? (a) rigid (b) wobbly
  16. 16.Which of these uses triangles? (a) a crane arm (b) a fort gateway (c) a slab over a canal (d) a round palace roof
  17. 17.Which of these uses a dome? (a) a plank over a drain (b) a roof truss (c) a planetarium roof (d) a crane arm
  18. 18.🔺 Which strong shape does a truss bridge side use? (a) arch (b) triangle (c) dome (d) beam
  19. 19.🔺 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?
  20. 20.True or false: a plank over a drain uses a dome. (a) False (b) True
  21. 21.🔺 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?
  22. 22.🔺 One side of a straw bridge is a row of 1 triangle standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  23. 23.🔺 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?
  24. 24.🔺 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
  25. 25.🔺 A beam bends under a load. Its top side is … (a) floating (b) stretched (tension) (c) not affected (d) squeezed (compression)
  26. 26.True or false: a lintel over a door uses a dome. (a) True (b) False
  27. 27.Which of these uses triangles? (a) a roof truss (b) a lintel over a door (c) an igloo (d) a round palace roof
  28. 28.True or false: a curved stone doorway uses a beam. (a) True (b) False
  29. 29.Which of these uses a dome? (a) a truss bridge side (b) a crane arm (c) a curved stone doorway (d) an igloo
  30. 30.True or false: a slab over a canal uses a beam. (a) True (b) False
  31. 31.🔺 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?
  32. 32.🔺 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?
  33. 33.🔺 Which strong shape does an old stone bridge use? (a) triangle (b) arch (c) dome (d) beam
  34. 34.🔺 Which strong shape does a round palace roof use? (a) triangle (b) dome (c) beam (d) arch
  35. 35.True or false: an electric pylon uses triangles. (a) False (b) True
  36. 36.🔺 Which strong shape does an electric pylon use? (a) beam (b) triangle (c) arch (d) dome
  37. 37.🔺 Which strong shape does a planetarium roof use? (a) dome (b) triangle (c) arch (d) beam
  38. 38.🔺 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
  39. 39.True or false: a shelf on two brackets uses a beam. (a) False (b) True
  40. 40.True or false: an old stone bridge uses an arch. (a) True (b) False

Answer key

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

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