Science 7
Structures Efficiency Review
Mr. Birt
Name_______________________________________ Class_____ Date___________________
1) Structural efficiency shows how much weight a structure can support compared to the
weight of the structure itself.
2) Structural efficiency is calculated by dividing the mass supported, by the mass of the
structure itself.
3) structural efficiency = mass supported (note: structural efficiency does not have units)
mass of structure
4) Example: A structure supports mass 8 grams. The structure weighs 4 grams.
Its structural efficiency = mass supported = 8 grams = 2
mass of structure
4 grams
Answer the following questions:
1. What two specific things does structural efficiency compare?
(1)___________________________________________________________________
(2)___________________________________________________________________
2. For many years, the Guinness Book of Records stated that the rhinoceros beetle was the
strongest beetle because it could support 850 times its own body weight. What is the beetle’s
structural efficiency?
___________________________
3. A 16 year old weight lifter weighed 60 kg (kilograms). He lifted and held 120 kg over his
head. Calculate his structural efficiency. Show your calculations.
4. A table weighing 10 kg was able to support 80 kg. Calculate the structural efficiency of the
table? (Show your calculations.)
5. A tower built of spaghetti and marshmallows was able to support 5 grams. The tower itself
weighed 10 grams. Calculate the tower’s structural efficiency. (Show your calculations)
6. a) Title the graph below Height versus Structural Efficiency
b) Label the X (horizontal) axis Height of Structure.
c) Label the Y (vertical) axis Structural Efficiency.
d) Graph the structural efficiency for each structure and label it as A, B, C, or D
e) Connect the points for the structural efficiencies you plotted in part d.
Height of Structure
Structure A
Structure B
Structure C
Structure D
Structural Efficiency
50 meters
130 meters
30 meters
90 meters
100
20
200
80
220
200
180
160
140
120
100
80
60
40
20
0
0
10
20 30
40
50
60
70
80
90 100 110 120 130 140
__________________________________________ (meters)
f) From the above results, what conclusion can you draw about the relationship between the
height of a structure and its structural efficiency? _____________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
g) Do you think this relationship would always be true for all structures?___________________
h) Why or why not? ____________________________________________________________
____________________________________________________________________________