Physics Help Forum Crumple zones in cars, safety equipment and thin sponges

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 Jan 15th 2009, 04:17 PM #1 Junior Member   Join Date: Jan 2009 Posts: 1 Crumple zones in cars, safety equipment and thin sponges Hello! I have a few questions that would be awesome if someone could answer.... 1. An egg dropped from 1m, for example, will break if it lands on concrete, but not if it lands on a thin sponge, even thought they experience the same impulse from each drop. WHY? 2. I have heard that cars today are designed with "crumple zones". How does this protect the occupants of the car? 3. For example, in football, safety equipment is very important in protecting the player. How do what they wear minimize their risk of injury and how has it affected the sport? Thanks so much for helping!
Jan 17th 2009, 09:49 PM   #2
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 Originally Posted by xo-hikari Hello! I have a few questions that would be awesome if someone could answer.... 1. An egg dropped from 1m, for example, will break if it lands on concrete, but not if it lands on a thin sponge, even thought they experience the same impulse from each drop. WHY? 2. I have heard that cars today are designed with "crumple zones". How does this protect the occupants of the car? 3. For example, in football, safety equipment is very important in protecting the player. How do what they wear minimize their risk of injury and how has it affected the sport? Thanks so much for helping!
For question 1, even though the impulse is the same. However, the rate of change of momentum(impulse) is not the same. For hard object, the impact time is very much smaller compared to soft surfaces, so the average force of impact acting on egg would smaller for soft land.

For question 2,3, the reasons are similar

 Jan 19th 2009, 07:56 AM #3 Junior Member   Join Date: Jan 2009 Posts: 3 F=(mv2-mv1)/t , this is implusive force Ft , this is impulse ... the egg didnt break when on soft surface is because the time of impact is lengthen, thus resulting the impulsive force to be smaller as t is greater ...(math) 3. safety equip (well it depends what type is it) but i suppose is the same subject we are talking about ... therefore safety equip helps to enlengthen the time of impact ... and also it serves as to protect us from frictional force as we fall on the ground ...
Jan 27th 2009, 10:31 PM   #4
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 Originally Posted by xo-hikari Hello! I have a few questions that would be awesome if someone could answer.... 1. An egg dropped from 1m, for example, will break if it lands on concrete, but not if it lands on a thin sponge, even thought they experience the same impulse from each drop. WHY? 2. I have heard that cars today are designed with "crumple zones". How does this protect the occupants of the car? 3. For example, in football, safety equipment is very important in protecting the player. How do what they wear minimize their risk of injury and how has it affected the sport? Thanks so much for helping!
The answer for 2 is that crumple zones on collision crumple and absorb the energy produced by the collision saving the occupants from harm.

Last edited by the curious; Jan 27th 2009 at 10:31 PM. Reason: typing error

 Tags cars, crumple, equipment, safety, sponges, thin, zones

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