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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 175 · 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) a planetarium roof (b) an igloo (c) an electric pylon (d) a fort gateway
  2. 2.🔺 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?
  3. 3.🔺 A beam bends under a load. Its top side is … (a) floating (b) stretched (tension) (c) not affected (d) squeezed (compression)
  4. 4.Which of these uses triangles? (a) an old stone bridge (b) a curved stone doorway (c) a crane arm (d) an igloo
  5. 5.🔺 Which strong shape does a lintel over a door use? (a) dome (b) beam (c) triangle (d) arch
  6. 6.🔺 Which strong shape does a curved stone doorway use? (a) triangle (b) dome (c) beam (d) arch
  7. 7.🔺 Which strong shape does an old stone bridge use? (a) beam (b) triangle (c) dome (d) arch
  8. 8.Which of these uses a beam? (a) a bicycle frame (b) an electric pylon (c) a truss bridge side (d) a lintel over a door
  9. 9.🔺 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?
  10. 10.Which of these uses triangles? (a) an old stone bridge (b) a planetarium roof (c) a curved stone doorway (d) a truss bridge side
  11. 11.🔺 How do engineers stop a square frame from wobbling? (a) paint it (b) take off a side (c) make it bigger (d) add a diagonal brace
  12. 12.Which of these uses a dome? (a) a shelf on two brackets (b) a planetarium roof (c) a lintel over a door (d) a bicycle frame
  13. 13.True or false: a fort gateway uses an arch. (a) False (b) True
  14. 14.🔺 Which strong shape does an electric pylon use? (a) arch (b) triangle (c) beam (d) dome
  15. 15.🔺 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?
  16. 16.🔺 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
  17. 17.True or false: a round palace roof uses a beam. (a) False (b) True
  18. 18.🔺 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?
  19. 19.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) triangle (c) square (d) hexagon
  20. 20.Which of these uses an arch? (a) a truss bridge side (b) an electric pylon (c) a bicycle frame (d) an old stone bridge
  21. 21.🔺 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?
  22. 22.True or false: a slab over a canal uses triangles. (a) False (b) True
  23. 23.🔺 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?
  24. 24.🔺 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
  25. 25.Which of these uses a beam? (a) an electric pylon (b) a planetarium roof (c) a plank over a drain (d) a curved stone doorway
  26. 26.True or false: an igloo uses an arch. (a) True (b) False
  27. 27.🔺 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?
  28. 28.🔺 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?
  29. 29.True or false: a planetarium roof uses a dome. (a) True (b) False
  30. 30.🔺 Which strong shape does a shelf on two brackets use? (a) triangle (b) dome (c) arch (d) beam
  31. 31.🔺 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?
  32. 32.🔺 Which strong shape does a truss bridge side use? (a) dome (b) beam (c) triangle (d) arch
  33. 33.🔺 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
  34. 34.Which of these uses triangles? (a) an old stone bridge (b) an igloo (c) a lintel over a door (d) a roof truss
  35. 35.🔺 Which strong shape does an igloo use? (a) arch (b) dome (c) beam (d) triangle
  36. 36.🔺 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?
  37. 37.🔺 Which strong shape does a planetarium roof use? (a) beam (b) arch (c) triangle (d) dome
  38. 38.True or false: a truss bridge side uses triangles. (a) True (b) False
  39. 39.True or false: a truss bridge side uses an arch. (a) False (b) True
  40. 40.True or false: a crane arm uses an arch. (a) False (b) True

Answer key

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

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