A Sampling of Effects Trivia Quiz

Answer: Accordion

This is an effect seen in congested road traffic leading up to traffic lights or roadworks. The braking and acceleration of the car at the front propagates down the line, often getting stronger as it goes. Misjudgements happen and accidents are not unheard of. In the 2020 Tuscan Grand Prix, a restart behind a safety car ended up with four mid-field vehicles colliding after getting caught out by the accordion effect. Other names include slinky effect, concertina effect and string instability.

Answer: Cheerios

Cheerios are a brand of breakfast cereal which happens to float on milk. Floating objects vary in buoyancy but broadly fall into two groups, those that are buoyant in the liquid (such as Cheerios) and those that normally sink but are kept afloat by surface tension. Each has a meniscus with the former lifting at the interface between liquid and object, and curved down for the latter. Like kinds are attracted to each other, but different kinds of floater will repel each other.

A similar effect will happen with the walls of the container, depending on whether the meniscus at the container's edge is upward or downward pointing and the kind of floater involved.

Answer: Brazil nut

Also known as the muesli effect, breakfast cereals or packets of mixed nuts with similar densities but different sized particles show granular convection behaviour when the contents are vibrated. This might be during transport from the manufacturer, for example. So the contents shift around with the big lumps tending to float to the top. This is a concern for breakfast cereal manufacturers.

The effect can be seen in some 'rubble' type asteroids, as a result of earthquakes and in formerly glaciated areas where frost heave deposits new boulders on the surface each year.

Answer: Hot chocolate

The effect is believed to occur because of the gas bubbles introduced by adding the powder. The effect of the bubbles is to reduce the speed of sound in the liquid. As the bubbles clear, the speed of sound increases again causing the pitch to increase. At 20 deg C (68 deg F), the speed of sound in water and air is 1,481 m/s (4.859 ft/s) and 343 m/s (1,215 ft/s) respectively, so the effect is perhaps not so surprising. The effect might be achieved when making instant coffee or possibly putting aerated water in a glass.

Answer: Leidenfrost

Where the temperature of the pan is at or above the Leidenfrost point, about 193 deg C (379 deg F) for water depending on impurities, the droplet creates an insulating vapour layer immediately under it which keeps the droplet hovering off the surface of the hot pan. Steam has a much poorer thermal conductivity than the metal of the pan so the steam effectively insulates the water droplet. It will skitter along the surface and take longer to boil off. The name comes from the German doctor who first described the effect.

Answer: Autokinetic

This is assumed to occur because a person's motion perception is normally tied to some reference point which is missing in the dark. It was described in 1799 by Alexander von Humboldt, who thought the apparent movement of stars he saw was real. He called it "Sternschwanken", meaning "swinging stars".

This was disproved in 1857 when several simultaneous observers of the same star showed no consistency in the direction of apparent movement or amplitude. In aviation, it is a well-known effect and causes problems when using refuelling tankers at night.

Answer: Cupertino

There is no connection to Apple Inc., as far as the writer is aware. Some dictionaries in early spellcheckers did not recognise the unhyphenated word 'Cooperation'. It was not part of their dictionary and the automatic replacement word was 'Cupertino', which now lends its name to the phenomenon. There are plenty of examples out there, such as "Voldemort" being replaced with "Voltmeter". A more recent variant is where some smartphones auto-correct what they see as possible mistakes.

Answer: Tamagotchi

Released in 1996, millions of these toys have been sold worldwide. The tamagotchi is an egg-shaped, handheld, virtual electronic pet which people looked after. People became personally invested in their devices, distracting themselves from their daily lives. School bans followed. Failing to look after it could result in its 'death', causing some distress.

It is not a stretch to see an unhealthy dependency occurring with AI software programmes. There are plenty of films that explore this idea.

Answer: Stack

The stack effect (also called the chimney effect) can be used for cooling and providing natural ventilation, not just removing smoke from fires. One of the advantages of such systems is that no power is required. They generally exploit variations in air buoyancy between indoors and outdoors, which are due to temperature and moisture differences. The sun can form part of the system by heating the air in a stack where it emerges through a roof. The air then rises, sucking air in from lower down the pipe. Painting the above-roof section a heat-absorbing colour can enhance this effect. A wind blowing across a pipe can also draw air out of the building.

Careless design can also have negative impacts such as loss of internal heat or increasing the hazards from fire, particularly in taller buildings. In well-sealed high-rise buildings, the stack effect can result in significant pressure differences which needs to be dealt with during the design phase, often by mechanical ventilation.

Answer: Lotus

When a water droplet touches a surface, adhesion forces normally result in the wetting of the surface. The structure of the lotus leaf at nanoscale is such that the adhesion force is significantly reduced, with as little as 0.6% of the water droplet in contact with the leaf. This also makes the droplet effective at picking up dirt, giving the leaf a self-cleaning ability. In some plants this helps with protection against pathogens and maintaining photosynthesis efficiency. Plants such as nasturtiums and prickly pears, and the wings of some insects also have this property.