Why Can't You Open Your Car Door If Someone is Trying to Unlock It at the Same Time?

iStock
iStock

At some point, everyone who rides in a car will experience the same awkward dance between a passenger and a driver: the door unlocking kerfuffle. One person pushes the button to try to unlock the car, while the person trying to get the door open pulls the handle at the same time. The car won’t unlock, and both passenger and driver have to repeat the process all over again—perhaps going through the whole procedure multiple times before successfully getting the timing right. Shouting may ensue.

According to Jalopnik, this inconvenient feature of all cars is the result of the very complicated mechanics behind automobile doors. To explain how, Jalopnik senior editor Jason Torchinsky and writer David Tracy opened up the door panels on two cars to see how each locking mechanism worked.

The simple answer is that the unlock button and pulling the door handle both trigger two different actions inside the door. “The most basic explanation possible is that pulling on the handle engages a little mechanical piece inside the door, a piece that bumps into another mechanical piece triggered by someone else trying to unlock the door,” Torchinksky and Tracy write. “Alone, either one would do their job unimpeded. Do both at the same time and they block each other.”

This is true in both older cars and newer models, though the latch systems have evolved over the years. These door locks include multiple links and latches that each have to coordinate to lock and unlock a car. Because the system that unlocks the door from the inside with a button and the system that unlocks it from the outside with a key are completely separate, they can’t both be engaged at the same time—kind of like how you can’t breathe and swallow at the same time.

For a closer look, you can see a door lock in action for yourself in this breathlessly narrated but useful YouTube video illustrating how the locks on a 2001 Toyota Corolla work.

If you’re mechanically inclined, head to Jalopnik for more details, including photos and graphics that allow you to see inside doors and get up-close with the locking mechanisms.

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Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

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Are Any of the Scientific Instruments Left on the Moon By the Apollo Astronauts Still Functional?

Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Heritage Space/Heritage Images/Getty Images

C Stuart Hardwick:

The retroreflectors left as part of the Apollo Lunar Ranging Experiment are still fully functional, though their reflective efficiency has diminished over the years.

This deterioration is actually now delivering valuable data. The deterioration has multiple causes including micrometeorite impacts and dust deposition on the reflector surface, and chemical degradation of the mirror surface on the underside—among other things.

As technology has advanced, ground station sensitivity has been repeatedly upgraded faster than the reflectors have deteriorated. As a result, measurements have gotten better, not worse, and measurements of the degradation itself have, among other things, lent support to the idea that static electric charge gives the moon an ephemeral periodic near-surface pseudo-atmosphere of electrically levitating dust.

No other Apollo experiments on the moon remain functional. All the missions except the first included experiment packages powered by radiothermoelectric generators (RTGs), which operated until they were ordered to shut down on September 30, 1977. This was done to save money, but also because by then the RTGs could no longer power the transmitters or any instruments, and the control room used to maintain contact was needed for other purposes.

Because of fears that some problem might force Apollo 11 to abort back to orbit soon after landing, Apollo 11 deployed a simplified experiment package including a solar-powered seismometer which failed after 21 days.

This post originally appeared on Quora. Click here to view.

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