Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 154 · 40 questions

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.

1. 1.🔺 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?
2. 2.🔺 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
3. 3.🔺 One side of a straw bridge is a row of 2 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 shape keeps its shape best when its corners are pinned? (a) triangle (b) square (c) hexagon (d) rectangle
5. 5.🔺 Which strong shape does a plank over a drain use? (a) triangle (b) arch (c) dome (d) beam
6. 6.Which of these uses an arch? (a) an old stone bridge (b) a crane arm (c) a bicycle frame (d) a shelf on two brackets
7. 7.True or false: a fort gateway uses an arch. (a) False (b) True
8. 8.🔺 Which strong shape does a truss bridge side use? (a) arch (b) triangle (c) beam (d) dome
9. 9.True or false: a planetarium roof uses a dome. (a) False (b) True
10. 10.True or false: an electric pylon uses an arch. (a) False (b) True
11. 11.Which of these uses a dome? (a) a truss bridge side (b) an electric pylon (c) a round palace roof (d) an old stone bridge
12. 12.Which of these uses a beam? (a) a fort gateway (b) an electric pylon (c) an igloo (d) a shelf on two brackets
13. 13.True or false: an electric pylon uses triangles. (a) False (b) True
14. 14.🔺 Which strong shape does a curved stone doorway use? (a) triangle (b) dome (c) beam (d) arch
15. 15.🔺 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?
16. 16.🔺 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) wobbly (b) rigid
17. 17.Which of these uses an arch? (a) a slab over a canal (b) a fort gateway (c) a round palace roof (d) a bicycle frame
18. 18.🔺 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?
19. 19.Which of these uses triangles? (a) a planetarium roof (b) a truss bridge side (c) a lintel over a door (d) a plank over a drain
20. 20.Which of these uses a dome? (a) an old stone bridge (b) a lintel over a door (c) a slab over a canal (d) an igloo
21. 21.True or false: a slab over a canal uses a beam. (a) False (b) True
22. 22.🔺 A beam bends under a load. Its top side is … (a) not affected (b) squeezed (compression) (c) floating (d) stretched (tension)
23. 23.🔺 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?
24. 24.Which of these uses a dome? (a) a slab over a canal (b) a planetarium roof (c) a crane arm (d) a plank over a drain
25. 25.🔺 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?
26. 26.🔺 Which strong shape does a roof truss use? (a) arch (b) triangle (c) beam (d) dome
27. 27.🔺 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?
28. 28.True or false: a planetarium roof uses an arch. (a) True (b) False
29. 29.🔺 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
30. 30.True or false: a shelf on two brackets uses an arch. (a) False (b) True
31. 31.🔺 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?
32. 32.True or false: a bicycle frame uses triangles. (a) False (b) True
33. 33.🔺 Which strong shape does a planetarium roof use? (a) dome (b) arch (c) beam (d) triangle
34. 34.True or false: a fort gateway uses triangles. (a) True (b) False
35. 35.🔺 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?
36. 36.🔺 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?
37. 37.🔺 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
38. 38.🔺 Why can an arch carry heavy loads? (a) it is hollow (b) it bends easily (c) it is very light (d) it works in compression
39. 39.Which of these uses triangles? (a) a slab over a canal (b) an igloo (c) a plank over a drain (d) a roof truss
40. 40.🔺 How do engineers stop a square frame from wobbling? (a) make it bigger (b) paint it (c) add a diagonal brace (d) take off a side

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