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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 599 · 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 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?
  2. 2.🔺 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?
  3. 3.🔺 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?
  4. 4.🔺 Which strong shape does an electric pylon use? (a) beam (b) dome (c) triangle (d) arch
  5. 5.🔺 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?
  6. 6.True or false: a lintel over a door uses triangles. (a) False (b) True
  7. 7.🔺 Which strong shape does a lintel over a door use? (a) dome (b) arch (c) beam (d) triangle
  8. 8.True or false: a slab over a canal uses a beam. (a) False (b) True
  9. 9.🔺 How do engineers stop a square frame from wobbling? (a) paint it (b) add a diagonal brace (c) make it bigger (d) take off a side
  10. 10.True or false: a crane arm uses a beam. (a) True (b) False
  11. 11.🔺 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?
  12. 12.🔺 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?
  13. 13.True or false: a truss bridge side uses triangles. (a) False (b) True
  14. 14.🔺 Which strong shape does an igloo use? (a) triangle (b) dome (c) arch (d) beam
  15. 15.🔺 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?
  16. 16.🔺 Which strong shape does a crane arm use? (a) arch (b) beam (c) triangle (d) dome
  17. 17.🔺 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?
  18. 18.Which of these uses triangles? (a) a lintel over a door (b) a round palace roof (c) a planetarium roof (d) a truss bridge side
  19. 19.True or false: a crane arm uses an arch. (a) True (b) False
  20. 20.🔺 Which strong shape does a truss bridge side use? (a) dome (b) arch (c) triangle (d) beam
  21. 21.🔺 A beam bends under a load. Its top side is … (a) stretched (tension) (b) floating (c) not affected (d) squeezed (compression)
  22. 22.🔺 Which strong shape does a round palace roof use? (a) dome (b) triangle (c) arch (d) beam
  23. 23.🔺 One side of a straw bridge is a row of 14 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  24. 24.🔺 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?
  25. 25.Which of these uses an arch? (a) a truss bridge side (b) a plank over a drain (c) an old stone bridge (d) a bicycle frame
  26. 26.🔺 Which shape keeps its shape best when its corners are pinned? (a) triangle (b) rectangle (c) hexagon (d) square
  27. 27.🔺 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?
  28. 28.🔺 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
  29. 29.🔺 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?
  30. 30.True or false: a curved stone doorway uses an arch. (a) True (b) False
  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) rigid (b) wobbly
  32. 32.🔺 Why can an arch carry heavy loads? (a) it is hollow (b) it bends easily (c) it is very light (d) it works in compression
  33. 33.🔺 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?
  34. 34.Which of these uses triangles? (a) a curved stone doorway (b) a round palace roof (c) an electric pylon (d) an igloo
  35. 35.True or false: a fort gateway uses an arch. (a) False (b) True
  36. 36.True or false: a bicycle frame uses an arch. (a) True (b) False
  37. 37.🔺 Which strong shape does a bicycle frame use? (a) arch (b) triangle (c) dome (d) beam
  38. 38.🔺 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?
  39. 39.True or false: a shelf on two brackets uses a beam. (a) False (b) True
  40. 40.True or false: an igloo uses an arch. (a) False (b) True

Answer key

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

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