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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 260 · 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 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?
  2. 2.🔺 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?
  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.🔺 A beam bends under a load. Its top side is … (a) squeezed (compression) (b) floating (c) not affected (d) stretched (tension)
  5. 5.🔺 Which strong shape does a fort gateway use? (a) triangle (b) dome (c) arch (d) beam
  6. 6.🔺 Which strong shape does a bicycle frame use? (a) triangle (b) arch (c) beam (d) dome
  7. 7.🔺 Which strong shape does a curved stone doorway use? (a) triangle (b) beam (c) arch (d) dome
  8. 8.🔺 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?
  9. 9.True or false: a lintel over a door uses a dome. (a) True (b) False
  10. 10.True or false: an electric pylon uses triangles. (a) False (b) True
  11. 11.🔺 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
  12. 12.🔺 Which shape keeps its shape best when its corners are pinned? (a) hexagon (b) square (c) rectangle (d) triangle
  13. 13.True or false: a lintel over a door uses triangles. (a) True (b) False
  14. 14.🔺 Which strong shape does an igloo use? (a) arch (b) beam (c) triangle (d) dome
  15. 15.🔺 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?
  16. 16.🔺 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
  17. 17.True or false: a crane arm uses an arch. (a) False (b) True
  18. 18.🔺 Why can an arch carry heavy loads? (a) it is hollow (b) it is very light (c) it works in compression (d) it bends easily
  19. 19.🔺 How do engineers stop a square frame from wobbling? (a) make it bigger (b) add a diagonal brace (c) take off a side (d) paint it
  20. 20.🔺 Which strong shape does a crane arm use? (a) beam (b) dome (c) triangle (d) arch
  21. 21.🔺 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
  22. 22.Which of these uses a beam? (a) a lintel over a door (b) a roof truss (c) an igloo (d) a bicycle frame
  23. 23.🔺 Which strong shape does a slab over a canal use? (a) dome (b) triangle (c) beam (d) arch
  24. 24.Which of these uses triangles? (a) an igloo (b) a plank over a drain (c) a lintel over a door (d) a bicycle frame
  25. 25.True or false: a lintel over a door uses a beam. (a) True (b) False
  26. 26.🔺 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?
  27. 27.🔺 Which strong shape does a lintel over a door use? (a) arch (b) triangle (c) dome (d) beam
  28. 28.🔺 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?
  29. 29.True or false: a curved stone doorway uses an arch. (a) True (b) False
  30. 30.🔺 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?
  31. 31.🔺 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?
  32. 32.Which of these uses a beam? (a) a plank over a drain (b) an igloo (c) a bicycle frame (d) a crane arm
  33. 33.Which of these uses triangles? (a) a plank over a drain (b) a round palace roof (c) a fort gateway (d) a roof truss
  34. 34.True or false: a plank over a drain uses triangles. (a) False (b) True
  35. 35.🔺 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?
  36. 36.Which of these uses a dome? (a) a bicycle frame (b) a roof truss (c) a slab over a canal (d) an igloo
  37. 37.Which of these uses triangles? (a) a planetarium roof (b) a truss bridge side (c) a slab over a canal (d) a fort gateway
  38. 38.🔺 Which strong shape does a planetarium roof use? (a) dome (b) triangle (c) beam (d) arch
  39. 39.🔺 One side of a straw bridge is a row of 8 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  40. 40.Which of these uses an arch? (a) an electric pylon (b) an old stone bridge (c) a roof truss (d) a crane arm

Answer key

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

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