Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 243 · 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 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?
2. 2.🔺 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?
3. 3.Which of these uses an arch? (a) an electric pylon (b) an old stone bridge (c) a shelf on two brackets (d) a lintel over a door
4. 4.🔺 How do engineers stop a square frame from wobbling? (a) paint it (b) add a diagonal brace (c) make it bigger (d) take off a side
5. 5.True or false: a truss bridge side uses triangles. (a) False (b) True
6. 6.🔺 Which strong shape does a shelf on two brackets use? (a) dome (b) triangle (c) arch (d) beam
7. 7.🔺 Which strong shape does a curved stone doorway use? (a) dome (b) triangle (c) arch (d) beam
8. 8.🔺 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) rigid (b) wobbly
9. 9.🔺 Which strong shape does a fort gateway use? (a) arch (b) dome (c) beam (d) triangle
10. 10.🔺 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?
11. 11.Which of these uses triangles? (a) a curved stone doorway (b) an old stone bridge (c) a crane arm (d) a plank over a drain
12. 12.Which of these uses a beam? (a) a bicycle frame (b) a shelf on two brackets (c) an igloo (d) a round palace roof
13. 13.Which of these uses an arch? (a) a fort gateway (b) a bicycle frame (c) a truss bridge side (d) a planetarium roof
14. 14.True or false: a round palace roof uses an arch. (a) False (b) True
15. 15.Which of these uses triangles? (a) a curved stone doorway (b) a slab over a canal (c) a truss bridge side (d) a lintel over a door
16. 16.🔺 A flat frame has 8 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
17. 17.Which of these uses a beam? (a) a truss bridge side (b) a planetarium roof (c) a plank over a drain (d) a roof truss
18. 18.🔺 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?
19. 19.Which of these uses a dome? (a) a bicycle frame (b) a curved stone doorway (c) a planetarium roof (d) an electric pylon
20. 20.🔺 Why can an arch carry heavy loads? (a) it bends easily (b) it works in compression (c) it is hollow (d) it is very light
21. 21.🔺 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?
22. 22.Which of these uses a dome? (a) a curved stone doorway (b) a bicycle frame (c) an electric pylon (d) an igloo
23. 23.🔺 Which strong shape does an igloo use? (a) triangle (b) beam (c) arch (d) dome
24. 24.True or false: a shelf on two brackets uses a dome. (a) False (b) True
25. 25.🔺 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
26. 26.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) square (c) triangle (d) hexagon
27. 27.🔺 Which strong shape does a crane arm use? (a) triangle (b) arch (c) beam (d) dome
28. 28.🔺 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
29. 29.🔺 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?
30. 30.Which of these uses a beam? (a) a round palace roof (b) a slab over a canal (c) an electric pylon (d) a roof truss
31. 31.True or false: an old stone bridge uses triangles. (a) True (b) False
32. 32.🔺 Which strong shape does a plank over a drain use? (a) dome (b) arch (c) beam (d) triangle
33. 33.True or false: a bicycle frame uses an arch. (a) False (b) True
34. 34.🔺 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?
35. 35.🔺 Which strong shape does a planetarium roof use? (a) triangle (b) dome (c) beam (d) arch
36. 36.Which of these uses an arch? (a) a crane arm (b) a round palace roof (c) a curved stone doorway (d) a bicycle frame
37. 37.🔺 Which strong shape does a lintel over a door use? (a) arch (b) triangle (c) dome (d) beam
38. 38.🔺 A beam bends under a load. Its top side is … (a) not affected (b) stretched (tension) (c) squeezed (compression) (d) floating
39. 39.True or false: a slab over a canal uses triangles. (a) True (b) False
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) rigid (b) wobbly

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