(why is there no off topic forum in these forums?)
Anyways, I'm trying to enlist some help in crosschecking if the conclusion at the bottom is true, based on the math.
Scenario: Kid fell off the slide in the playground from about 1.5m up.
Claim: Wife scolds the husband stating that a child falling from 1.5m would be equivalent to an adult falling from a rooftop.
So is this really true?
Assumptions for sake of proving a point: The kid is around 20kg, an average adult is around 80kg.
The potential energy (PE) a kid with a mass (m) of 20kg has at a height (g) of 1.5m would be PE = gmh ... ergo 9.81 * 20 * 1.5 = 294,3 Joules of Energy. That means when he falls that potential energy is converted to kinetic energy and he hits the ground with a force of 294,3 Joules.
The potential energy (PE) an adult with a mass (m) of 80kg has at a height (g) of 1.5m would be PE = gmh ... ergo 9.81 * 80 * 1.5 = 1177,2 Joules of Energy. That means when he falls that potential energy is converted to kinetic energy and he hits the ground with a force of 1177,2 Joules.
So comparing the ratio between the two, 1177,2 / 294,3 = 4, this means the adult will hit the ground 4 times harder than the kid when dropped from the same height.
Turning this around a bit we can then also say that adults energy of 1177,2 = 9,81 * 20 * X ... solve for X we get X =1177,2 / 9,81 * 29 and X = 6.
In other words... for a kid of 20kg to experience the same energy that an adult falling from 1.5m does the kid would have to fall from 6 meters.
So my conclusion is: It hurts more for an adult to fall 1.5m than it does for a kid... and we don't have to worry about kids falling down from something unless they fall from a 3rd floor window or higher.
Anyways, I'm trying to enlist some help in crosschecking if the conclusion at the bottom is true, based on the math.
Scenario: Kid fell off the slide in the playground from about 1.5m up.
Claim: Wife scolds the husband stating that a child falling from 1.5m would be equivalent to an adult falling from a rooftop.
So is this really true?
Assumptions for sake of proving a point: The kid is around 20kg, an average adult is around 80kg.
The potential energy (PE) a kid with a mass (m) of 20kg has at a height (g) of 1.5m would be PE = gmh ... ergo 9.81 * 20 * 1.5 = 294,3 Joules of Energy. That means when he falls that potential energy is converted to kinetic energy and he hits the ground with a force of 294,3 Joules.
The potential energy (PE) an adult with a mass (m) of 80kg has at a height (g) of 1.5m would be PE = gmh ... ergo 9.81 * 80 * 1.5 = 1177,2 Joules of Energy. That means when he falls that potential energy is converted to kinetic energy and he hits the ground with a force of 1177,2 Joules.
So comparing the ratio between the two, 1177,2 / 294,3 = 4, this means the adult will hit the ground 4 times harder than the kid when dropped from the same height.
Turning this around a bit we can then also say that adults energy of 1177,2 = 9,81 * 20 * X ... solve for X we get X =1177,2 / 9,81 * 29 and X = 6.
In other words... for a kid of 20kg to experience the same energy that an adult falling from 1.5m does the kid would have to fall from 6 meters.
So my conclusion is: It hurts more for an adult to fall 1.5m than it does for a kid... and we don't have to worry about kids falling down from something unless they fall from a 3rd floor window or higher.
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