Car Talk - Strange but true; don't slam on brakes with escaped hummingbird in car

postandcourier ^ | Sunday, May 24, 2009

[JoeProBono]

Q. Once, on a very long, boring trip, my passenger and I were reduced to asking each other dumb questions. We came upon one question that we couldn't settle. Imagine that I'm driving along at highway speed with the air conditioner on and the windows closed.

A hummingbird that was caged in the back seat gets loose, and with nowhere really to go, it ends up just hovering there in midcar. Our question is this: If I hit the brakes hard, does the hummingbird crash into the windshield?

My friend said of course it would, that its momentum would cause it to keep moving forward as the car slowed. But I, being the more educated of us (not necessarily a good thing, as my friend claimed), said that the hummingbird's position would depend on its air speed, not its ground speed, and as the car slowed down, the air inside the car would slow down at an equal rate, as would the hummingbird, thereby avoiding becoming windshield splatter. So guys, please settle this question so I can finally get some sleep.

[JoeProBono]

TOM: Why don't you just put the darn hummingbird back in its cage?

RAY: As your friend says, over-education might not always be a good thing. But when you work around my brother, you come to the inescapable conclusion that a little bit more education can never hurt.

TOM: The answer is that the hummingbird is toast. He crashes into the windshield. As your friend correctly says, in summarizing Newton’s first law, objects in motion will stay in motion.

RAY: The cabin air is part of the car. So if the hummingbird is hovering in that air while the car is in motion, the bird has the same horizontal speed as the car.

TOM: That means he’s in motion. And when the car stops, the hummingbird does not, and splat.

RAY: Now, as we were discussing your question, Ross, my brother raised an interesting issue.

TOM: That’s right. I said, “What about cigar smoke?” Let's say I’m motoring along in one of the new cars that we test-drive, smoking a huge cigar.

RAY: Of course, this is a hypothetical question, because you’re not allowed to smoke in the test cars.

TOM: I’m not? Oh! I’m not! Right. But let’s say, just for the sake of argument, that the smoke is hovering in the air all around me, and I stop short. Does the smoke crash into the windshield? I don’t think so.

RAY: It’s a good question. So we called in our Car Talk physicist, professor Wolfgang Rueckner, who also moonlights at Harvard University.

TOM: Wolfgang says that the smoke, too, is subject to Newton’s first law, and should crash into the windshield. The only reason it doesn’t is because it doesn't have enough mass. So while it’s heading toward the windshield, it bangs into nearby air molecules, and the effect is muted.

RAY: I’m wondering if Newton ever tried this physics experiment: Take a test car that my brother has been smoking a cigar in, and have the manufacturer who owns it stick his head inside and take a sniff. Then see if that guy slams my brother’s head into the windshield.

[Paladin2]

A helium balloon goes the opposite way.

[Always Right]

The hummingbird crashes into the windshield. The air speed may help the hummingbird some, but his momentum will carry him forward. Hummingbirds are fast enough that perhaps he could adjust though, but that movement would be from the work from his wings and not the air speed.

[Fichori]

I believe a hummingbird can accelerate/decelerate faster than any car normally can.

So, if the bird had the mind to, it could avoid hitting the windshield.

The reason the smoke doesn't hit the windshield is because it weighs the same as the air its suspended in. (the hummingbird is heavier, but is also maneuverable)


So, if you hit the breaks, the bird would either splat on the windshield, or commence retrograde acceleration to avoid hitting the aforementioned glass.

[LiberConservative]

The hummingbird is traveling at the same speed as your car. When you apply the brakes the bird’s inertia will force it into the windshield. It’s called “inertia”. Try it with a tennis ball. Have someone in the back seat toss it up while you put on the brakes. The ball will fall forward - like everything else in the car that isn’t tied down.

[John123]

If I hit the brakes hard, does the hummingbird crash into the windshield?

Sounds like the perfect question to ask Obama at the golf course today...

[tet68]

Have someone in the back seat throw up while you put on the brakes and see what happens.

Yes bobby, THAT was physics.

[Always Right]

Sounds like the perfect question to ask Obama at the golf course today...

The answer will be dependent upon which one of the 57 states it happens in.

[D Rider]

(speaking to your posted dialog):

Ray, if your theory is true, you could get rid of seatbelts and airbags, as long as you keep the windows are rolled up.

[smokingfrog]

splat!

[Daffynition]

I love it! The data can be extrapolated.

This has already been hashed out the classic question with Strouhal numbers and simplified flight waveforms...by "Estimating the Airspeed Velocity of an Unladen Swallow"

For a European Swallow flying with our estimated wingbeat amplitude of 24 cm, the predicted pattern of cruising flight ranges from a Strouhal number (St) of 0.2:

... to a less efficient 0.4:

If the first diagram (St = 0.2) is accurate, then the cruising speed of the European Swallow would be roughly 16 meters per second (15 beats per second * 1.1 meters per beat). If the second diagram (St = 0.4) is accurate, then the cruising speed of the European Swallow would be closer to 8 meters per second (15 beats per second * 0.55 meters per beat).

If we settle on an intermediate Strouhal value of 0.3:

We can estimate the airspeed of the European Swallow to be roughly 11 meters per second (15 beats per second * 0.73 meters per beat).

[kbennkc]

If the bird is on the cell phone , I hope it dies . They don't taste like chicken , more like tiny whooping cranes or bald eagles.

[huldah1776]

Tell the bird to buckle up.

[dainbramaged]

I’m not much at crunching numbers, but hummingbirds are tough
little critters and could survive a good whack. Depends on the whack, of course.

[potlatch]

This remindes me of the ‘elevator’ question, lol.

Say you’re in an elevator and it breaks and falls many stories to the ground.

Are you saved if you JUMP just as it hits the ground? Lol

[DannyTN]

The bird will slam into the back of your head when you hit the brakes, causing you to hit the gas and then crash at high speed killing everyone in both vehicles except the bird who was cushioned in the collision by you.

[devolve]

.

Only if you have a bungee cord attached to the top of the elevator

[potlatch]

I think you kinda get smacked into the roof anyway.

Lol, just realized I had pinged on two bird threads!

[goat granny]

Since I am not afraid of asking dumb questions, what if the hummingbird is facing the back of the car and hovering?

[JoeProBono]

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