What if there's a bird flying inside the truck?

Question

Will the truck get more weight as the bird standing?

Answer 1

It will be the same. You should really refer to mass rather than weight. All bodies have inertia due to their mass so the the whole truck is overcoming the inertia of all the masses in the truck to move. THIS IS THE SAME WHETHER THE BIRD IS SITTING OR FLYING.

Proof

http://kwc.org/mythbusters/2007/04/episo...

Myth: If birds in a truck fly, does the truck get lighter?

Story: A guy is travelling behind a big truck. Everytime the truck comes up to a bridge, the driver gets out, bangs on the side of the truck, and then proceeds to drive across. He asks the driver at a gas station why he was doing this -- the driver explained that he was over the weight limit for most of the bridges, so he was banging to make the birds fly and make the truck lighter.

Newton's 3rd Law of Motion: For every action, there is an equal and opposite reaction.

Small-scale test

Adam and Jamie did their best to catch pigeons with bread and seeds, but they ended up getting two pidgeons delivered instead.

Bird Chamber 1: Adam's first bird flying chamber was a tall clear chamber with a piece of mesh on the floor that Adam could vibrate to make the birds fly. The entire chamber was set on top of a scale to measure the weight difference when the birds fly. The vibrating mesh wasn't enough encouragement to keep the birds in the air, which lead to Bird Chamber 2.

Bird Chamber 2: Jamie replaced Adam's vibrating mesh floor with a rotating weed-whacker-like foam tube (not strong enough to hurt). Adam also built the camber much larger so that the birds would have more room to fly. They still had no luck keeping "Jackson" the pidgeon airborne.

R/C Helicopter test

Adam and Jamie were having enough trouble with the bird that they decided to use a R/C helicopter instead. They had their decision to switch to a helicopter validated by Ilkka Koskelo (Physicist, SFSU), who explained that both birds and helicopters are using the same physical principles to fly (i.e. Newton's 3rd Law).

Adam bult a new rig that allowed the helicopter to lift-off but also attached it to a set of poles to keep it centered. The scale on the rig showed 52.6 regardless of whether or not the helicopter was flying on or the ground.

Full-scale test

Setup: * Small trailer rigged with a two larger versions of Jamie's rotating foam tubes * Load cells positioned at each corner to measure the shifting trailer weight * 11lbs of pigeons. Catching the more pigeons was a mini-segment. First, Jamie tried to use Jackson and bird seed as a lure for more pigeons but had little luck. They upgraded to a pnuematic "web shooter". The shooter fired six tennis balls that were tethered to a net. They had little luck with the web shooter as the pigeons flew away long before the net reached them. Adam and Jamie finally gave up and called the pigeon wrangler to deliver more birds.

Most of the birds stayed in the air as they released them. The measurements from the load cell had a little bit of noise but the conclusion was clear: the flying birds did not make the trailer lighter.

Helicopter test: M5 employee Chris was brought in to fly a large model R/C helicopter inside the trailer. The first helicopter myth didn't go well -- the helicopter blades hit the side of the trailer and broke. Chris retrieved another R/C helicopter and on the second test they got the result they wanted: no difference in the weight of the trailer as the helicopter took off.

busted (Newton's Third Law is upheld)

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