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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 294 · 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 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?
  2. 2.True or false: a roof truss uses a dome. (a) False (b) True
  3. 3.🔺 One side of a straw bridge is a row of 6 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
  4. 4.🔺 Which strong shape does a plank over a drain use? (a) dome (b) beam (c) arch (d) triangle
  5. 5.🔺 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
  6. 6.🔺 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?
  7. 7.🔺 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?
  8. 8.🔺 Which strong shape does an old stone bridge use? (a) triangle (b) dome (c) beam (d) arch
  9. 9.🔺 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?
  10. 10.True or false: a bicycle frame uses triangles. (a) True (b) False
  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 of these uses triangles? (a) an old stone bridge (b) a curved stone doorway (c) a roof truss (d) a shelf on two brackets
  13. 13.🔺 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?
  14. 14.🔺 Which shape keeps its shape best when its corners are pinned? (a) hexagon (b) triangle (c) rectangle (d) square
  15. 15.🔺 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?
  16. 16.Which of these uses a dome? (a) a lintel over a door (b) a shelf on two brackets (c) a slab over a canal (d) an igloo
  17. 17.🔺 Why can an arch carry heavy loads? (a) it is hollow (b) it works in compression (c) it is very light (d) it bends easily
  18. 18.🔺 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) wobbly (b) rigid
  19. 19.True or false: a bicycle frame uses a dome. (a) True (b) False
  20. 20.True or false: an electric pylon uses triangles. (a) False (b) True
  21. 21.🔺 Which strong shape does a crane arm use? (a) triangle (b) arch (c) beam (d) dome
  22. 22.🔺 Which strong shape does a fort gateway use? (a) beam (b) triangle (c) dome (d) arch
  23. 23.True or false: a fort gateway uses a beam. (a) False (b) True
  24. 24.True or false: a planetarium roof uses a dome. (a) False (b) True
  25. 25.🔺 Which strong shape does a curved stone doorway use? (a) arch (b) triangle (c) dome (d) beam
  26. 26.🔺 A beam bends under a load. Its top side is … (a) not affected (b) stretched (tension) (c) squeezed (compression) (d) floating
  27. 27.🔺 How do engineers stop a square frame from wobbling? (a) paint it (b) make it bigger (c) take off a side (d) add a diagonal brace
  28. 28.Which of these uses triangles? (a) a plank over a drain (b) a bicycle frame (c) a lintel over a door (d) a curved stone doorway
  29. 29.🔺 Which strong shape does a roof truss use? (a) beam (b) arch (c) dome (d) triangle
  30. 30.True or false: a roof truss uses triangles. (a) False (b) True
  31. 31.True or false: a plank over a drain uses a beam. (a) False (b) True
  32. 32.Which of these uses a dome? (a) a curved stone doorway (b) a planetarium roof (c) an old stone bridge (d) a slab over a canal
  33. 33.True or false: a curved stone doorway uses an arch. (a) False (b) True
  34. 34.Which of these uses an arch? (a) a round palace roof (b) an old stone bridge (c) a bicycle frame (d) a roof truss
  35. 35.🔺 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?
  36. 36.🔺 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
  37. 37.🔺 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?
  38. 38.🔺 Which strong shape does a bicycle frame use? (a) dome (b) beam (c) triangle (d) arch
  39. 39.True or false: a bicycle frame uses a beam. (a) True (b) False
  40. 40.True or false: a crane arm uses a dome. (a) True (b) False

Answer key

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

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