Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 133 · 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 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?
2. 2.🔺 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?
3. 3.🔺 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?
4. 4.True or false: a curved stone doorway uses triangles. (a) True (b) False
5. 5.Which of these uses a dome? (a) a crane arm (b) a curved stone doorway (c) a bicycle frame (d) a round palace roof
6. 6.🔺 One side of a straw bridge is a row of 11 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
7. 7.🔺 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
8. 8.🔺 Which strong shape does a shelf on two brackets use? (a) beam (b) dome (c) triangle (d) arch
9. 9.🔺 How do engineers stop a square frame from wobbling? (a) make it bigger (b) take off a side (c) add a diagonal brace (d) paint it
10. 10.🔺 Which strong shape does a roof truss use? (a) dome (b) triangle (c) arch (d) beam
11. 11.🔺 Which strong shape does an old stone bridge use? (a) beam (b) triangle (c) dome (d) arch
12. 12.🔺 One side of a straw bridge is a row of 10 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
13. 13.🔺 Which strong shape does a curved stone doorway use? (a) arch (b) triangle (c) beam (d) dome
14. 14.🔺 A beam bends under a load. Its top side is … (a) not affected (b) floating (c) stretched (tension) (d) squeezed (compression)
15. 15.🔺 Why can an arch carry heavy loads? (a) it is hollow (b) it is very light (c) it bends easily (d) it works in compression
16. 16.🔺 Which shape keeps its shape best when its corners are pinned? (a) hexagon (b) triangle (c) rectangle (d) square
17. 17.🔺 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?
18. 18.🔺 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
19. 19.🔺 Which strong shape does a planetarium roof use? (a) triangle (b) arch (c) beam (d) dome
20. 20.🔺 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?
21. 21.🔺 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?
22. 22.True or false: a shelf on two brackets uses an arch. (a) False (b) True
23. 23.Which of these uses triangles? (a) a lintel over a door (b) an electric pylon (c) a shelf on two brackets (d) an old stone bridge
24. 24.Which of these uses a beam? (a) an old stone bridge (b) a roof truss (c) a crane arm (d) a lintel over a door
25. 25.🔺 Which strong shape does a fort gateway use? (a) triangle (b) arch (c) dome (d) beam
26. 26.Which of these uses a dome? (a) a fort gateway (b) a roof truss (c) an igloo (d) a shelf on two brackets
27. 27.🔺 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
28. 28.Which of these uses a beam? (a) a truss bridge side (b) a slab over a canal (c) a fort gateway (d) a curved stone doorway
29. 29.Which of these uses a beam? (a) a fort gateway (b) a plank over a drain (c) a crane arm (d) a roof truss
30. 30.🔺 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?
31. 31.True or false: a roof truss uses an arch. (a) True (b) False
32. 32.🔺 Which strong shape does a plank over a drain use? (a) dome (b) triangle (c) beam (d) arch
33. 33.🔺 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?
34. 34.Which of these uses an arch? (a) a lintel over a door (b) a round palace roof (c) an old stone bridge (d) a planetarium roof
35. 35.🔺 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?
36. 36.🔺 Which strong shape does a bicycle frame use? (a) dome (b) beam (c) arch (d) triangle
37. 37.True or false: a crane arm uses an arch. (a) True (b) False
38. 38.🔺 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) wobbly (b) rigid
39. 39.🔺 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
40. 40.🔺 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) wobbly (b) rigid

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