# Naked Science Forum

## General Science => General Science => Topic started by: JimBob on 28/04/2013 20:29:04

Title: How much energy??
Post by: JimBob on 28/04/2013 20:29:04
How much energy is involved in this quote from a Wikipedia page. ----- [Rocky] "Marciano's punch was tested and it was featured in the December 1963 issue of Boxing Illustrated: "Marciano's knockout blow packs more explosive energy than an armour-piercing bullet and represents as much energy as would be required to spot lift 1000 pounds one foot off the ground."[19][20]" 1000 foot pounds??????????????????????????????????????????????? Joules???????? newton???????
Title: Re: How much energy??
Post by: damocles on 01/05/2013 22:42:37
Very little! Reading a quotation is a very low energy operation. [;D]

However, to return to the question of Marciano's punch, I will first translate into SI units and then do the calculation:
450 kg * 0.3 m * 9.8 m/s2 = 1.32 kJ.
This is not an implausible amount, in view of the fact that a normal diet involves several thousand kJ per day.
"explosive energy" might mean "power" which would be measured in watt and involve a time for the delivery, but is more likely just journalistic hype.
"newton" is a unit of force rather than energy. "foot pounds" are an obsolete unit no longer understood by anyone but Americans.
Title: Re: How much energy??
Post by: AndroidNeox on 12/05/2013 23:41:55
"foot pounds" are an obsolete unit no longer understood by anyone but Americans.

It's left over from back when we were a scientifically advanced nation.
;)
Title: Re: How much energy??
Post by: evan_au on 13/05/2013 11:40:26
Rocky weighed 185 pounds or 84 kg.
(See http://coxscorner.tripod.com/rocky.html)

If he could put his whole body into a punch, he would be traveling at 5.6 m/s to deliver 1.3 kJ.

However, it's much more likely that the mass behind the punch would be less than a quarter of this, so the punch velocity would have to be at least doubled.