Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 38 · 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.🔺 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
2. 2.Which of these uses a dome? (a) a bicycle frame (b) a slab over a canal (c) an igloo (d) a lintel over a door
3. 3.True or false: an electric pylon uses a dome. (a) True (b) False
4. 4.🔺 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?
5. 5.🔺 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?
6. 6.🔺 Which strong shape does a planetarium roof use? (a) arch (b) beam (c) triangle (d) dome
7. 7.🔺 Which strong shape does a curved stone doorway use? (a) triangle (b) beam (c) arch (d) dome
8. 8.🔺 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?
9. 9.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) triangle (c) hexagon (d) square
10. 10.🔺 One side of a straw bridge is a row of 5 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
11. 11.🔺 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?
12. 12.🔺 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
13. 13.🔺 A beam bends under a load. Its top side is … (a) not affected (b) stretched (tension) (c) squeezed (compression) (d) floating
14. 14.🔺 How do engineers stop a square frame from wobbling? (a) add a diagonal brace (b) make it bigger (c) paint it (d) take off a side
15. 15.Which of these uses an arch? (a) a bicycle frame (b) a round palace roof (c) a fort gateway (d) a planetarium roof
16. 16.🔺 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?
17. 17.🔺 Which strong shape does a shelf on two brackets use? (a) dome (b) triangle (c) arch (d) beam
18. 18.🔺 Which strong shape does a lintel over a door use? (a) dome (b) arch (c) beam (d) triangle
19. 19.Which of these uses an arch? (a) an old stone bridge (b) an igloo (c) a planetarium roof (d) an electric pylon
20. 20.True or false: an igloo uses a dome. (a) False (b) True
21. 21.Which of these uses triangles? (a) an igloo (b) an electric pylon (c) a lintel over a door (d) a fort gateway
22. 22.🔺 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
23. 23.🔺 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
24. 24.Which of these uses triangles? (a) a shelf on two brackets (b) a lintel over a door (c) an old stone bridge (d) a roof truss
25. 25.True or false: an electric pylon uses triangles. (a) False (b) True
26. 26.🔺 A frame shaped like a hexagon is made of straws joined by loose pins, with 2 corner-to-corner braces. Is it rigid or wobbly? (a) rigid (b) wobbly
27. 27.Which of these uses a dome? (a) a plank over a drain (b) a slab over a canal (c) a round palace roof (d) a roof truss
28. 28.🔺 Which strong shape does a roof truss use? (a) beam (b) arch (c) triangle (d) dome
29. 29.🔺 Which strong shape does an electric pylon use? (a) dome (b) arch (c) beam (d) triangle
30. 30.Which of these uses triangles? (a) a curved stone doorway (b) a lintel over a door (c) an igloo (d) a crane arm
31. 31.Which of these uses a beam? (a) an old stone bridge (b) a shelf on two brackets (c) a crane arm (d) an igloo
32. 32.🔺 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?
33. 33.🔺 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?
34. 34.True or false: an electric pylon uses a beam. (a) False (b) True
35. 35.Which of these uses an arch? (a) a bicycle frame (b) a plank over a drain (c) a curved stone doorway (d) an igloo
36. 36.🔺 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
37. 37.🔺 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?
38. 38.🔺 Which strong shape does an old stone bridge use? (a) arch (b) dome (c) beam (d) triangle
39. 39.🔺 Which strong shape does a fort gateway use? (a) dome (b) beam (c) arch (d) triangle
40. 40.🔺 A frame shaped like a hexagon is made of straws joined by loose pins, with 0 corner-to-corner braces. Is it rigid or wobbly? (a) wobbly (b) rigid

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