OS
OpenStem
@openstem · Joined Jul 2026
7420 public items8 groups
Flashcards8 cards
Name a familiar object whose size is standardized, and explain why that matters.1 / 8
Many answers work — a light bulb's screw base, a phone charging cable, a sheet of paper, a bicycle tire valve. Standardizing the size means the object works with equipment made by many different companies.
Engineering · L2 · Standards & Codes
@openstem
Engineering · L2 · Standards & CodesFlashcards9 cards
What is a cantilever?1 / 9
A cantilever is a beam or structure that is fixed (supported) at only one end and sticks out into open space, free and unsupported at the other end.
Engineering · L2 · What Makes a Cantilever
@openstem
Engineering · L2 · What Makes a CantileverFlashcards9 cards
Why is a diving board a cantilever?1 / 9
It is bolted down at one end (the fixed end at the pool deck) and sticks out over the water completely unsupported (the free end) — exactly the cantilever shape.
Engineering · L2 · Cantilevers in the Real World
@openstem
Engineering · L2 · Cantilevers in the Real WorldFlashcards11 cards
What is a capacitor?1 / 11
A capacitor is a component that stores electrical charge. It can hold that charge for a while, and then release it — often very, very quickly.
Engineering · L2 · What Does a Capacitor Do?
@openstem
Engineering · L2 · What Does a Capacitor Do?Flashcards8 cards
What happens to a liquid's temperature-lowering effect when it evaporates off a surface?1 / 8
The surface cools down. Turning from liquid to gas takes energy, and the evaporating liquid pulls that energy out of whatever it is touching as heat.
Engineering · L2 · Evaporative Cooling Basics
@openstem
Engineering · L2 · Evaporative Cooling BasicsFlashcards8 cards
What is a swamp cooler (evaporative air cooler)?1 / 8
A machine that blows air through a wet pad before sending it into a room. Water evaporating from the pad pulls heat out of the air passing through, so the air that reaches the room is cooler than the air that went in.
Engineering · L2 · Engineering Evaporative Cooling
@openstem
Engineering · L2 · Engineering Evaporative CoolingFlashcards10 cards
What is water filtration?1 / 10
Filtration is the process of removing unwanted particles and contaminants from water by passing it through a material that physically traps or chemically absorbs them, leaving cleaner water on the other side.
Engineering · L2 · How Water Filtration Works
@openstem
Engineering · L2 · How Water Filtration WorksFlashcards10 cards
What is a "requirement", in engineering terms?1 / 10
A specific, written statement of something the finished design must be able to do — a rule the design has to satisfy, decided before any building or drawing starts.
Engineering · L2 · Requirements Gathering
@openstem
Engineering · L2 · Requirements GatheringFlashcards8 cards
A backpack design lists: "must fit in an airplane's overhead bin" and "has a hidden pocket for sunglasses." Which requirement, if missed, means the design has failed its purpose?1 / 8
Not fitting in the overhead bin — that's the must-have. A traveler who can't carry the bag onto the plane has a design that failed its core purpose, even if the hidden pocket is a nice touch.
Engineering · L2 · Requirements Gathering
@openstem
Engineering · L2 · Requirements GatheringFlashcards10 cards
What is a paper or cardboard mockup?1 / 10
A rough physical model built from paper, cardboard, and tape — something an engineer can put together in minutes to check size, shape, and layout.
Engineering · L2 · Prototyping Methods: The Basics
@openstem
Engineering · L2 · Prototyping Methods: The BasicsFlashcards9 cards
What question does a paper/cardboard mockup answer best?1 / 9
"Does this look and feel right?" It's great for checking overall size, shape, and layout before spending time on anything more precise.
Engineering · L2 · Choosing the Right Prototyping Method
@openstem
Engineering · L2 · Choosing the Right Prototyping MethodFlashcards10 cards
What is a bending moment?1 / 10
A bending moment is a turning effect that bends a beam. At any point along the beam it equals a force multiplied by its perpendicular distance from that point: M = F × d.
Engineering · L3 · Beam Bending
@openstem
Engineering · L3 · Beam BendingFlashcards8 cards
Between a solid circular rod and a hollow tube of the same mass and material, which resists bending better?1 / 8
The hollow tube. Removing material from the centre (near the neutral axis) and moving it outward increases bending resistance for the same amount of material.
Engineering · L3 · Beam Bending
@openstem
Engineering · L3 · Beam BendingFlashcards10 cards
What is the method of joints?1 / 10
A way to find the force in every member of a truss by isolating one joint (pin) at a time, treating it as a particle in static equilibrium, and writing ΣFx = 0 and ΣFy = 0 for the forces meeting there.
Engineering · L3 · Method of Joints
@openstem
Engineering · L3 · Method of JointsFlashcards8 cards
A simple triangular truss has a pin support at A, a roller support at B directly 8 m to the right, and an apex joint C sitting above the midpoint, 3 m up. A 600 N load pushes straight down at C. What are the vertical reactions at A and B?1 / 8
300 N up at each support. The truss and the load are both symmetric about the midpoint, so the total 600 N load splits evenly between the two supports.
Engineering · L3 · Method of Joints — Worked Example
@openstem
Engineering · L3 · Method of Joints — Worked ExampleFlashcards11 cards
State Ohm's Law.1 / 11
V = IR — voltage equals current times resistance.
Engineering · L3 · Ohm's Law & Power
@openstem
Engineering · L3 · Ohm's Law & PowerFlashcards10 cards
What does an operational amplifier (op-amp) do, in one sentence?1 / 10
It amplifies the difference between its two input voltages — the output is proportional to (V+ − V−), scaled by a huge internal gain.
Engineering · L3 · Op-Amps
@openstem
Engineering · L3 · Op-AmpsFlashcards7 cards
Rf = 4 kΩ, Rin = 2 kΩ. What is the non-inverting gain?1 / 7
Gain = 1 + 4/2 = 1 + 2 = 3
Engineering · L3 · Op-Amps — Gain Calculations
@openstem
Engineering · L3 · Op-Amps — Gain CalculationsFlashcards10 cards
What does volumetric flow rate Q measure, and what's its formula?1 / 10
Q is the volume of fluid passing a cross-section per unit time:
Engineering · L3 · Flow Rate
@openstem
Engineering · L3 · Flow RateFlashcards10 cards
Why does a solid material get longer when it is heated?1 / 10
Heat makes the atoms in the material vibrate more vigorously and push each other slightly farther apart on average, so the material's overall dimensions grow.
Engineering · L3 · Thermal Expansion
@openstem
Engineering · L3 · Thermal ExpansionFlashcards6 cards
An aluminum rod is 2 m long at 15 °C. Aluminum's α ≈ 2.4 × 10⁻⁵ /°C. Find ΔL if it warms to 45 °C.1 / 6
ΔT = 30 °C. ΔL = 2.4 × 10⁻⁵ × 2 × 30 = 0.00144 m ≈ 1.44 mm.
Engineering · L3 · Thermal Expansion
@openstem
Engineering · L3 · Thermal ExpansionFlashcards9 cards
What is a design trade-off?1 / 9
Giving up some amount of one desirable quality to gain more of another — for example, accepting more weight to get more strength. Almost no design can maximize every quality at once.
Engineering · L3 · Design Trade-offs
@openstem
Engineering · L3 · Design Trade-offsFlashcards10 cards
What is destructive testing?1 / 10
Testing that damages or destroys the part being tested in order to find its true limits — for example, pulling a metal sample until it snaps.
Engineering · L3 · Quality Control & Testing
@openstem
Engineering · L3 · Quality Control & TestingFlashcards7 cards
What is a "batch" in manufacturing?1 / 7
A group of units made together under the same conditions — for example, one production run of 10,000 bolts made from the same steel on the same day.
Engineering · L3 · Quality Control & Testing
@openstem
Engineering · L3 · Quality Control & TestingFlashcards9 cards
What is torque, and what is its formula?1 / 9
Torque is a turning effect produced by a force acting around a pivot. It is calculated as τ = F × d, where F is the applied force and d is the perpendicular distance from the pivot to the line along which the force acts.
Engineering · L3 · Torque & Wrenches
@openstem
Engineering · L3 · Torque & WrenchesFlashcards8 cards
A mechanic applies 40 N at a perpendicular distance of 0.25 m from a bolt. What torque is produced?1 / 8
τ = F × d = 40 N × 0.25 m = 10 N·m.
Engineering · L3 · Torque & Wrenches
@openstem
Engineering · L3 · Torque & WrenchesFlashcards8 cards
What is the center of mass of an object?1 / 8
The single point where an object's mass can be treated as if it were all concentrated — the balance point. If you could support the object at exactly that point, it would balance in any orientation.
Engineering · L3 · Center of Mass & Stability
@openstem
Engineering · L3 · Center of Mass & StabilityFlashcards7 cards
What formula gives the center of mass of two point masses along a line?1 / 7
The weighted average of their positions: x_cm = (m₁x₁ + m₂x₂) / (m₁ + m₂). Each mass's position is weighted by how much mass it carries, so heavier masses pull the center of mass toward themselves.
Engineering · L3 · Center of Mass & Stability
@openstem
Engineering · L3 · Center of Mass & StabilityFlashcards10 cards
What quantity does a capacitor store, and what equation relates it to voltage?1 / 10
A capacitor stores charge Q. It relates to the voltage across it by Q = CV, where C is the capacitance in farads.
Engineering · L3 · Capacitors & Energy Storage
@openstem
Engineering · L3 · Capacitors & Energy StorageFlashcards9 cards
What is the difference between a digital signal and an analog signal?1 / 9
A digital signal only ever takes discrete states — usually just 0 (off/low) and 1 (on/high). An analog signal can take any value across a continuous range, like a volume dial that can sit anywhere between 'off' and 'max'.
Engineering · L3 · Digital Logic Gates
@openstem
Engineering · L3 · Digital Logic Gates