Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 148 · 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 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?
2. 2.Which of these uses an arch? (a) a crane arm (b) a shelf on two brackets (c) an old stone bridge (d) a slab over a canal
3. 3.Which of these uses a beam? (a) a truss bridge side (b) a round palace roof (c) a plank over a drain (d) an electric pylon
4. 4.🔺 Why can an arch carry heavy loads? (a) it is hollow (b) it is very light (c) it works in compression (d) it bends easily
5. 5.Which of these uses a beam? (a) a round palace roof (b) a roof truss (c) a shelf on two brackets (d) an old stone bridge
6. 6.Which of these uses triangles? (a) a lintel over a door (b) a shelf on two brackets (c) a crane arm (d) an igloo
7. 7.🔺 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?
8. 8.Which of these uses a dome? (a) an old stone bridge (b) a planetarium roof (c) a roof truss (d) a slab over a canal
9. 9.True or false: a shelf on two brackets uses a beam. (a) True (b) False
10. 10.🔺 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?
11. 11.🔺 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
12. 12.Which of these uses triangles? (a) an electric pylon (b) a slab over a canal (c) a lintel over a door (d) a shelf on two brackets
13. 13.🔺 A beam bends under a load. Its top side is … (a) stretched (tension) (b) not affected (c) floating (d) squeezed (compression)
14. 14.🔺 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?
15. 15.🔺 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
16. 16.🔺 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?
17. 17.🔺 How do engineers stop a square frame from wobbling? (a) make it bigger (b) take off a side (c) paint it (d) add a diagonal brace
18. 18.True or false: an electric pylon uses triangles. (a) False (b) True
19. 19.Which of these uses triangles? (a) a curved stone doorway (b) a round palace roof (c) an old stone bridge (d) a roof truss
20. 20.🔺 Which strong shape does an electric pylon use? (a) dome (b) triangle (c) beam (d) arch
21. 21.🔺 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?
22. 22.True or false: a round palace roof uses a beam. (a) True (b) False
23. 23.🔺 Which strong shape does a truss bridge side use? (a) dome (b) arch (c) beam (d) triangle
24. 24.🔺 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?
25. 25.🔺 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?
26. 26.🔺 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
27. 27.🔺 Which strong shape does a lintel over a door use? (a) dome (b) arch (c) beam (d) triangle
28. 28.Which of these uses triangles? (a) a lintel over a door (b) a planetarium roof (c) a fort gateway (d) a truss bridge side
29. 29.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) hexagon (c) triangle (d) square
30. 30.🔺 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?
31. 31.🔺 Which strong shape does a plank over a drain use? (a) dome (b) arch (c) beam (d) triangle
32. 32.🔺 Which strong shape does a planetarium roof use? (a) arch (b) beam (c) dome (d) triangle
33. 33.🔺 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?
34. 34.Which of these uses an arch? (a) a bicycle frame (b) an igloo (c) a fort gateway (d) a truss bridge side
35. 35.🔺 Which strong shape does a roof truss use? (a) triangle (b) beam (c) arch (d) dome
36. 36.🔺 Which strong shape does an igloo use? (a) arch (b) beam (c) dome (d) triangle
37. 37.True or false: a crane arm uses an arch. (a) True (b) False
38. 38.🔺 Which strong shape does a curved stone doorway use? (a) triangle (b) beam (c) arch (d) dome
39. 39.🔺 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?
40. 40.🔺 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?

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