Structures 1
List the 3 structural forms. BONUS for everyone (don't say it, write it down): Which is typically the strongest of the three? 15 sec.
Solid/mass Structure (strongest, made from piling e.g. brick wall), Frame Structure (rigid arrangement of parts fastened together, e.g. skeleton), Shell Structure (only strong if made correctly, thin outer layer, e.g. snail shell)
What is the term for this definition: "can withstand some damage and not break." 15 sec.
RESILIENCE
What units are force and mass measured in RESPECTIVELY? 15 sec.
Newtons (N) and kg, g, lbs, etc.
What is the difference between mass and weight (definition wise, not its matter of units)? 20 sec.
mass is the amount of matter in an object. wherever the object is, its mass never changes.
weight is the force of gravity acting upon the object. it can change depending on what planet you're on as it depends on the force of gravity.
What is the difference between tension and torsion? 15 sec
Tension is a pulling force whereas torsion is twisting
What's the definition of a structure? BONUS (don't say it, write it down): What are the 2 types of structures? 20 sec.
Structure is anything made from one or more parts that performs a function. Usually structures must support a MASS.
2 types: Natural and manufactured.
What is the relationship between form and function? 15 sec.
FUNCTION leads to FORM
Definition of a "force." 15 sec.
"a push or a pull that tends to cause an object to change its movement or shape"
What is the force equation (must know what each letter means in the equation)? BONUS for everyone (don't say it, write it down): Assuming there is no resistance, what is the amount of acceleration in m/s^2?
15 sec to think.
F = ma
Force = mass x acceleration
9.81 m/s^2
Give an example of a shearing force. 15 sec
e.g. scissors cutting paper
Explain "margin of safety." 15 sec.
"limits within which a structure’s safety performance is felt to be acceptable." in other words, is the structure reasonably safe?
What 4 things is concrete COMPOSED of? BONUS for everyone (don't say it, write it down): Why is concrete widely used (cannot say "because it's strong/durable") 30 sec.
water, sand/aggregate, gravel, cement.
Can say any 1 of these reasons: cheap, versatile, fire resistant, low maintenance, easy to use, can fit into any shape.
What is "structural stability?" 15 sec.
ability to maintain its position even if FORCE is acted on it.
what is the definition of "centre of gravity?" BONUS for everyone (write it down): approximately, in most individuals, where is a human's centre of gravity? 25 sec.
Centre of Gravity (COG): The point in any solid where a single applied force could support it; the point where the mass of the object is equally balanced.
COG Tends to be around the belly button in most humans, but it depends on their overall structure e.g. height, size of limbs, how they are standing, etc.
What is Mr. Banco's favourite colour?
he can confirm
List and explain any 1 factor to consider when choosing materials. 30 seconds.
- Cost: will inexpensive material you use allow the structure to perform its function over a reasonable time?
- Appearance/Aesthetic: does the structure look "pleasing" over time?
- Environmental Impact: will this structure harm the environment?
- Energy efficiency: does it conserve energy?
- Consumer demand and availability
- Disposal of waste
From these shapes: rectangle, triangle, and square
What is the strongest shape? Explain.
triangle because it spreads out the force the best out of the three, and therefore does not bend when you apply pressure to it.
Show with your hands, the 4 types of INTERNAL forces. Hint: Thumb direction. 20 sec.
Tension: thumbs away from each other
Compression: thumbs towards each other
Shear: thumbs in opposing directions
Torsion: twisting
the effect of a force depends on WHAT 3 things, and WHY for each one? 30 sec
- magnitude (strength) of the force: strong vs weak force.
- direction of the force: where the force is COMING FROM matters because if i'm standing on a tightrope, a force coming from my side would push me over but a force coming from the front of me would be less likely to do so.
- location where the force is applied: WHERE you apply the force matters e.g. trying to push someone over, but you only push their toe.
Give one example each of:
- a natural moveable joint
- a manufactured moveable joint OR a rigid manufactured joint
25 sec
- a natural moveable joint: e.g. elbow
- a manufactured moveable joint e.g. door hinge
- a rigid manufactured joint e.g. welded joint in a bike
If a structure has "structural strength," will it ALWAYS have "structural stability?" Similarly, if a structure has "structural stability," will it ALWAYS have "structural strength?" EXPLAIN. 20 sec.
No. A structure could be strong but unstable, just as it could be stable but not strong.
Give 1 advantage AND 1 disadvantage for a solid/mass, frame, OR shell structure. 40 seconds.
MASS:
Advantages - held in place by their own weight, losing small amounts of material has little effect on overall stability
Disadvantages - require a lot of material, not suitable for some functions. Not much space in it for anything useful.
FRAME:
Advantages - Use relatively little material so can be made for less money, Easy to design and build, Much Lighter, Resilient (can withstand some damage and not break
Disadvantages - Materials must be joined in some way (this is often where the weakness is), Not the strongest shape.
SHELL:
Advantages - Use very little material & they are hollow inside so they are ideal as containers, Very strong
Disadvantages - A small weakness or imperfection can cause the structure to fail, Can be difficult to find materials to shape evenly into shell structures, NOT RESILIENT, When the shell is formed from hot or moist materials, uneven cooling can cause some parts to break
FREE FOR ALL: what is my name? (it's okay if the spelling is wrong)
Miss Krista
FREE FOR ALL: write your answer down.
True or false: Assuming there is no resistance, if an object has more mass, it will have a faster acceleration to the ground. Hint: think about the units. 30 sec.
BONUS: give a reason for your answer.
F = m / a
Acceleration is
a = F / m
Now plug in the gravitational force:
a = (m · g) / m = g
The masses cancel out, so both objects get the same acceleration g ≈ 9.81 m/s² (ignoring air resistance).
That’s why a bowling ball and a golf ball fall side-by-side in a vacuum.
Analogy: Pushing shopping carts
A big heavy cart is harder to push.
A small light cart is easier to push, but you also push less hard on it.
Because the extra push for the light cart and the extra heaviness for the heavy cart cancel out, both carts speed up the same.
If I push on the centre of a marshmallow, what two forces are occurring and where are they occurring? 20 sec