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sarah

Joined: 13 Oct 2009
Posts: 1
Location: United States

 Posted: Tue Nov 24, 2009 10:53 pm    Post subject: Egg Drop Catching Device I need help with a project...I have to build a device using only paper, cardboard, and small amounts of tape that will catch an egg without breaking it. The device can only be 7cm high and 30 cm wide, and the egg is dropped from 1, 2, and 3m. We are learning about impulse now - I know I need to increase the duration of the impact. A few people said I should just crumple up lots of pieces of paper and put that into a cardboard box - will that work? Any other suggestions?
hepcj

Joined: 23 Jun 2007
Posts: 125

 Posted: Wed Nov 25, 2009 4:19 pm    Post subject: Yes I think it will work provided the paper can deform enough to increase the time over which the momentum of the egg changes. Impulse is the Force x time taken. The falling egg has a certain momentum depending on the mass and the velocity. To change that momentum requires a force. (Force is rate of change of momentum). The average force on the egg will be F = (momentum just before egg touches paper - 0)/time taken When the egg falls it builds up a momentum and this will change from some value to 0. If it does this quickly then the average force on the egg is large and so it will break. The scrunched up paper in the box will increase the time taken for the egg to slow down by deforming, absorbing the energy of the collision. If you slow the egg down over a long enough time it won't break. Stunt men use cardboard boxes when jumping off high buildings to increase the time taken for them to change their momentum. I remember as a child making origami cubes out of paper and a layer or two of these in a box would also probably work.
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