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Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 321 · 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.🔺 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?
  2. 2.🔺 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
  3. 3.🔺 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?
  4. 4.🔺 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?
  5. 5.True or false: a lintel over a door uses triangles. (a) True (b) False
  6. 6.🔺 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?
  7. 7.🔺 Which strong shape does a crane arm use? (a) arch (b) beam (c) triangle (d) dome
  8. 8.🔺 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?
  9. 9.🔺 A beam bends under a load. Its top side is … (a) stretched (tension) (b) squeezed (compression) (c) not affected (d) floating
  10. 10.🔺 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
  11. 11.🔺 Which strong shape does a bicycle frame use? (a) arch (b) beam (c) dome (d) triangle
  12. 12.True or false: a planetarium roof uses a beam. (a) True (b) False
  13. 13.Which of these uses triangles? (a) a plank over a drain (b) a planetarium roof (c) a crane arm (d) a lintel over a door
  14. 14.🔺 Why can an arch carry heavy loads? (a) it is very light (b) it bends easily (c) it works in compression (d) it is hollow
  15. 15.🔺 Which strong shape does a roof truss use? (a) beam (b) dome (c) arch (d) triangle
  16. 16.True or false: a bicycle frame uses triangles. (a) True (b) False
  17. 17.Which of these uses a dome? (a) a truss bridge side (b) a plank over a drain (c) a curved stone doorway (d) a planetarium roof
  18. 18.🔺 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?
  19. 19.🔺 Which strong shape does a truss bridge side use? (a) arch (b) dome (c) triangle (d) beam
  20. 20.🔺 Which strong shape does an old stone bridge use? (a) triangle (b) dome (c) beam (d) arch
  21. 21.🔺 Which strong shape does an igloo use? (a) triangle (b) beam (c) arch (d) dome
  22. 22.Which of these uses an arch? (a) an igloo (b) a truss bridge side (c) a curved stone doorway (d) a roof truss
  23. 23.True or false: an electric pylon uses triangles. (a) True (b) False
  24. 24.🔺 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) rigid (b) wobbly
  25. 25.🔺 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?
  26. 26.🔺 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
  27. 27.True or false: a truss bridge side uses a dome. (a) True (b) False
  28. 28.True or false: a bicycle frame uses a beam. (a) True (b) False
  29. 29.True or false: a lintel over a door uses a dome. (a) True (b) False
  30. 30.True or false: a shelf on two brackets uses an arch. (a) True (b) False
  31. 31.True or false: a planetarium roof uses a dome. (a) True (b) False
  32. 32.🔺 Which strong shape does an electric pylon use? (a) arch (b) beam (c) dome (d) triangle
  33. 33.True or false: a truss bridge side uses triangles. (a) True (b) False
  34. 34.True or false: a fort gateway uses a dome. (a) False (b) True
  35. 35.🔺 Which strong shape does a round palace roof use? (a) arch (b) dome (c) beam (d) triangle
  36. 36.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) triangle (c) square (d) hexagon
  37. 37.Which of these uses a dome? (a) a lintel over a door (b) a slab over a canal (c) a bicycle frame (d) an igloo
  38. 38.🔺 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) rigid (b) wobbly
  39. 39.True or false: a crane arm uses a beam. (a) False (b) True
  40. 40.🔺 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

Answer key

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

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