At-home key-drop experiments

My favorite responses from the key-drop at-home experiments… I’m reminded at how complex the task of observation can be.

After the waste basket. I think this will happen because normally when i let things go while running, they tend to fly “backwards”. So if I release the keys in front of the waste basket then the keys will fly backwards into the garbage can… No no no no. I had it backwards. Things released will continue forward. So when I did this I released it from behind the garbage can and it ended up traveled in a bit of an arc into the garbage can.


My keys are pretty heavy, so I’ll choose right above the basket. It worked for me!  Landed in the trash can that is, makes sense but if my keys were lighter I would drop them before the trash can so they would arc into it.


After the basket, because I feel like the wind and speed from running forward will drag the keys slightly backwards… It was actually before the basket! I feel now that it is because there is so much momentum moving forward you must drop the keys before


I think that if you are running past the waste basket that you should drop your keys right after you pass the wastebasket. Since you are running forwards the keys will go in a diagonal and go into the basket…  No it is not what I expected. The keys would go into the basket if I dropped them before the wastebasket. The keys obviously aren’t going to go backwards when I am moving forwards.




I asked my roommate, [so-and-so] (she says hi!), to perform this experiment with me. We discovered that we needed to drop the keys before running by the wastebasket in order to make sure the keys landed in the wastebasket. The forward force of running with the keys towards the wastebasket continues slightly when you let go of the keys. Therefore, they continue to travel forward for a short distance while in freefall.


As i thought i had to drop the keys just before i passed the basket so the that they didn’t go past the waste basket.  I would like to think that since your carrying the keys they still have a velocity even though their not moving, so once separated from your hand they take on the outside acceleration and start to gain its own velocity for a different direction.


When I got my family involved with this activity, they had predicted that I would have to release my keys right above the wastebasket. They said that the weight of they keys and the momentum wouldn’t matter due to the fact that the keys weren’t being thrown. After testing our hypothesis, we found out that what we originally predicted was right. If you run holding your keys out then you would have to release the keys right above the basket in order for the keys to land in it. Releasing the keys before the box and after the box would land the keys in those spots before or after the box.

4 thoughts on “At-home key-drop experiments

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  1. I asked my boys (12 and 5) this same questions while reading this post. They both predicted that I would be right over the basket. I read some of the other predictions to them, but they stuck with their original. The interesting part, for me, was how I struggled not to tell them the answer! I realized how much more they’d learn from the experiment, but I also knew they weren’t going to get up and do it right away (if at all). Part of me wanted to make sure they didn’t go around with the wrong understanding, but another part realized that they’d learn it better (eventually) when they did the experiment.

  2. Brian,
    Did you follow up with the class to discuss these difficulties with observation and then perhaps encourage them to film the experiment to try to resolve some of these discrepancies?

    1. It’s a really good idea… if it weren’t a summer course, I think I’d try it. We continued the discussion by settling it with observation together and then discussing where the ball lands with respect to our feet… 😉

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