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Gr. 7 - Structures & Forces: Section 2.0 Quiz

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32 questions

Section 2 – External and Internal Forces Act on Structures

2.1 Measuring Forces

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A force is a push or a pull that tends to cause an object to change its...

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The actual effect of a force depends on three things: the magnitude, or size of the force; the direction of
the force; and ...

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In structural drawings, arrows represent forces. A force that is being applied to a heavy box to lift it off the ground would be shown by the following arrow ...

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A large force is applied to a freezer to move it up a ramp to the second floor, where a smaller force is
used to push it to the window, and a very large force is needed to lift it up, to put it off balance, so it falls out the window and is demolished on the sidewalk below.

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The standard unit of measuring force is named after a famous English scientist, who the first one to
describe the ‘law of gravitation’, getting the idea for the law as he sat under an apple tree. This unit of
measuring force is similar to the amount of force needed to hold an apple in your hand and is called a ...

2.2 External Forces Acting on Structures

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An external force is a force applied to a structure by ...

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Identify which structure would have the greatest stability, because of its centre of gravity.

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The Leaning Tower of Pisa is an example of a mass structure. The Tower was built with a lean originally
and it had been getting worse, because of the foundation on which it was built. The structure has not
fallen over yet, because its center of gravity still keeps it relatively stable. Once it started to lean more,
engineers knew that the center of gravity shifted. The reason that the Tower is moving is because ...

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A student compared his mass and weight in two different places (Vancouver and Banff). Which statement is correct?

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Weight is a force that is measured by the gravitational pull on the object. It is usually measured in ...

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Symmetry is a balanced arrangement of mass that occurs on opposite sides of a line or plane, or around
a centre or axis. The force of gravity acting on each side is the same. Which of the following illustrations
is symmetrical?

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Which of the following structures would have the greatest stablility?

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An external force on a structure is called a ...

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This bridge cannot perform its function any longer because it has collapsed. One of
the probable causes of the failure of this structure was the actual weight of the bridge, which
could not be supported by its suspension cables. This type of load is called ...

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A dynamic load on this train bridge is the ...

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Designers generally use three key methods to help structures withstand forces. They include all of the
methods below, EXCEPT for ...

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When engineers build bridges, they take two conditions into account: what the bridge is crossing and
what kinds of loads it will support, to decide which type of bridge will best suit the situation. Which type of bridge would engineers suggest to withstand very heavy loads?

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How well a structure will hold up under a load is important for cost, efficiency and ...

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Performance requirements are the guiding principles that engineers use to design structures. Maximum
weight that the structure can support is expressed as ...

2.3 Internal Forces Within Structures

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Internal forces are classified by the direction in which they act within an object. A force that acts to push parts of the object in contact with each other in opposite directions is this kind of internal force ...

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When a solid material is compressed, small microscopic cracks in the material can enlarge or break apart. This can cause one section of the material to break away from the other part. This action is called ...

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Structures fail for a number of reasons. Engineers, study failed structures so they can design stronger,
more durable structures. A flagpole that has been blown over in a strong wind happens because of the
increased force that is applied to the ...

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Metal fatigue happens because metal is ...

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Complementary forces happen when different kinds of forces act on a structure at the same time. An
example of a complementary force is ...

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When you put your hands on your desk and put all your weight on them - then try to move
them forward your hand (much like a structure) resists movement forward because of ...

2.4 Designing Structures

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The 7 wonders of the Ancient World took many years to complete, but they lasted a very long time. Why
do you think that the Statue of Zeus at Olympia lasted so long?

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The strongest structural shape is a...

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When a structure has a single horizontal load-bearing beam, supported by two columns - one at each
end, the beam will likely bend in the middle (A box and girder bridge spanning a river is a good example). This bending exerts pressure outward on the vertical supporting beams. To strengthen this bridge, so that heavy vehicle can cross it, you should ...

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An arch, which is a common shape in bridges, can support large loads. This is possible because the
force of the load is carried down through the arch to the foundation, from this point in the arch ...

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Beams are common components in a wide range of structures. The advantage of I beams is that they
have a lot of strength but have less of this compared to simple beams ...

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Structural stability requires that a variety of materials should to be utilized to avoid deformation and
structural failure. In a hang-glider the way that helps to reduce internal forces, such as tension,
compression and shear, on the component parts is to ...

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Auto safety designers and inspectors to identify impact points when material fails in a collision use crash test dummies. When the car is rammed into a solid wall, the front end buckles. This happens to better protect the Crash test dummies (us) in a real accident. The metal deforms because of the energy it absorbs in the impact. Designers ...