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Q & A: relative hummingbird

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Most recent answer: 01/22/2011
If I was in my car going 60 mph and a hummingbird was in the car also, and it was hovering, what spped would it be flying and why? Thanks
- Chris (age 12)
Tracy, CA

Hi Chris!

The answer to your question depends on what you mean.  You may have heard of Einsteinís Theory of Relativity - the main point Einstein is making is that we can only measure things (like speed, in this case) if we know where we are observing them from.

For instance, imagine Fred is in the car with the hummingbird and it is hovering right in front of his nose, and ten seconds later, Fred is still in the car and the hummingbird is still right in front of his nose.  Relative to Fred, the hummingbird is going zero miles per hour.  The car may be moving at 60 miles per hour, but Fred doesnít care about the car, only the hummingbird.

But Lucy is watching the car from a tree top.  Relative to Lucy, the hummingbird is going the same speed as the car when the car passes her.  To her, it looks like Fred is also going the same speed as the car.  Everything in the car is going the same speed as the car.

That is, everything in the car is going the same speed as the car as long as it is NOT moving *relative to the car*.

Hope this helps!


(published on 10/22/2007)

Follow-Up #1: hummingbird in car

In regards to chris' question about the hummingbird in the vehicle....I have a question: if the hummingbird is NOT staying in one spot in the car and moves forward...does this mean it is moving FASTER than the car? (at 60 mph or any speed I guess)?
- jefff f.r. (age 29)
fall river
Yes, relative to the earth the hummingbird would be moving faster than the car.

Mike W.

(published on 01/22/2011)

Follow-up on this answer.