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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 242 · 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 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?
  2. 2.🔺 Why can an arch carry heavy loads? (a) it is hollow (b) it works in compression (c) it bends easily (d) it is very light
  3. 3.🔺 Which strong shape does a roof truss use? (a) arch (b) beam (c) dome (d) triangle
  4. 4.🔺 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?
  5. 5.🔺 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
  6. 6.🔺 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) wobbly (b) rigid
  7. 7.🔺 Which strong shape does a bicycle frame use? (a) arch (b) beam (c) dome (d) triangle
  8. 8.Which of these uses an arch? (a) a truss bridge side (b) an igloo (c) an old stone bridge (d) a plank over a drain
  9. 9.🔺 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?
  10. 10.🔺 A beam bends under a load. Its top side is … (a) not affected (b) stretched (tension) (c) floating (d) squeezed (compression)
  11. 11.🔺 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?
  12. 12.Which of these uses an arch? (a) a shelf on two brackets (b) a planetarium roof (c) a curved stone doorway (d) a crane arm
  13. 13.🔺 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?
  14. 14.🔺 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?
  15. 15.🔺 Which strong shape does an old stone bridge use? (a) beam (b) dome (c) arch (d) triangle
  16. 16.🔺 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?
  17. 17.🔺 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
  18. 18.🔺 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
  19. 19.🔺 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?
  20. 20.🔺 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) wobbly (b) rigid
  21. 21.🔺 How do engineers stop a square frame from wobbling? (a) make it bigger (b) take off a side (c) paint it (d) add a diagonal brace
  22. 22.True or false: an igloo uses a dome. (a) True (b) False
  23. 23.🔺 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?
  24. 24.True or false: a plank over a drain uses an arch. (a) True (b) False
  25. 25.True or false: a lintel over a door uses a dome. (a) True (b) False
  26. 26.True or false: a shelf on two brackets uses a dome. (a) False (b) True
  27. 27.True or false: a truss bridge side uses triangles. (a) True (b) False
  28. 28.🔺 Which strong shape does a crane arm use? (a) beam (b) triangle (c) dome (d) arch
  29. 29.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) triangle (c) square (d) hexagon
  30. 30.True or false: a planetarium roof uses a dome. (a) True (b) False
  31. 31.🔺 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?
  32. 32.True or false: a crane arm uses a dome. (a) True (b) False
  33. 33.True or false: a crane arm uses triangles. (a) True (b) False
  34. 34.🔺 Which strong shape does a shelf on two brackets use? (a) dome (b) triangle (c) beam (d) arch
  35. 35.Which of these uses triangles? (a) an igloo (b) a fort gateway (c) a roof truss (d) a planetarium roof
  36. 36.🔺 Which strong shape does a plank over a drain use? (a) dome (b) triangle (c) beam (d) arch
  37. 37.Which of these uses a dome? (a) a fort gateway (b) a crane arm (c) a slab over a canal (d) a round palace roof
  38. 38.True or false: a planetarium roof uses triangles. (a) True (b) False
  39. 39.🔺 Which strong shape does a lintel over a door use? (a) dome (b) triangle (c) beam (d) arch
  40. 40.🔺 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?

Answer key

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

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