Why Is a Bullet More Damaging Than Falling Out of Bed?

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Homework Help Overview

The discussion revolves around comparing the kinetic energy of a bullet to the gravitational potential energy of a person falling from a height of 1 meter. The context includes calculations related to kinetic and potential energy, specifically using the formulas for each type of energy.

Discussion Character

  • Mathematical reasoning, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to calculate the kinetic energy of a bullet and the potential energy of a person in bed, raising questions about the accuracy of their calculations and the reasoning behind the comparative damage caused by a bullet versus a fall.

Discussion Status

Participants have provided feedback on the calculations, with one noting a typographical error in the speed used. The original poster seeks clarification on the terminology used in their explanation of why a bullet is more damaging and expresses a desire to ask further questions related to the topic.

Contextual Notes

There is a focus on ensuring the calculations adhere to significant figures, and participants are exploring the implications of energy types in the context of physical impact.

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1. Bond's usual gun of choice in every movie is a Walther PPK (except when he can get his hands on a machine gun
which blows up more guys). A bullet like this has a mass of around 15g and leaves the gun at 288m/s. Calculate the
kinetic energy in a bullet like this.
2.Aside from shooting bad guys, Bond has a lot off success with, ummm, the ladies. Imagine he is resting in bed one morning
1 m off the ground and that his mass is 63.5 kg. What is his potential energy relative to the ground when he in bed?
3. Do answers from (1) and (2) surprise you? Why is a bullet more damaging than falling out of bed from a height of 1 m?

2. I think i have to use the formula of kinetic energy. Kinetic energy = (mv^2)2 and gravitational potential energy = mgh
sorry i can't use the codes properly so i wrote it this way :redface:

3. For number 1 i did

E_k=(mv^2)/2
= (0.015)(288^2)/2
=622.05 J
=6.22 x 10^2 J
so the kinetic energy is 6.22 x 10^2 J
Is this approximation correct since the question has 3 sig figs?

for number 2 i did

Eg=mgh
=63.5 x 9.80 x 1
=622.3 J
=6.22 x 10^2 J
so the gravitational potential enegry is 6.22 x 10^2 J
Is it also appropriate?

for number 3 i wrote
A bullet is more damaging than falling out of bed from height of 1 m because a bullet with its smaller surface area causes more impact on the small area thus creating more damage where is the pressure by falling one meter is spread through the whole body enabling the body to dissipate the damage and get less hurt.

Is it accurate?
 
Last edited:
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looks fine, except that you wrote different speeds, 288 and 228 :)
 
thank you.sorry that was a typing error. so is my third answer correct i mean is it alright to use those terms i used? also can i ask some more questions related to this topic in here? :)
thank you very much
 
Kinetic energy is 1/2 mv^2
 
mgb_phys said:
Kinetic energy is 1/2 mv^2
yes i did write that :)
i just wrote the whole thing and divided by two :)
 

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