 April 4, 2011

### Monday “Did you know…?” The gravity of the situation?

It’s suspected that for every pound overweight, it’s like adding 3-5lbs to the hip, knee, ankle joints…so go 10lbs over weight, that’s feeling like an extra 30-50 lbs on the joints. Not to mention the imbalanced strain it puts on places like the lower back, shoulders, etc…throwing everything out of whack leading to those nagging aches/pains. • WIcasa Yatapika April 5, 2011 Reply

The change in potential energy is the work done when a mass is raised or lowered in a gravitational field. If the mass is raised, then some “force” must act upon it to push the mass “uphill” against the pull of gravity, and the potential energy of the mass has therefore increased. The energy is called “potential” because it can be completely recovered (in principle), by allowing the mass to fall downhill again. If the mass falls freely, then the mass speeds up as it falls, and the PE at the top of the hill is converted to kinetic energy at the bottom. Alternately, the mass might push against some other object (like a person) as it falls and transfer its energy to the second mass. If a mass of (m) kilograms is raised or lowered by height “h” in meters then the change in gravitational potential energy is (m x g x h), where “g” is the acceleration of gravity (9.8 m/s^2) in the SI system. (Note: the conversion of mass to weight is accomplished thru multiplying by the acceleration of gravity, which yields the units N-m) The change in PE is measured in Joules in this case. A weight of “p” pounds raised or lowered by “f” feet has a change in PE of (p x f), which is measured in foot-pounds, since the weight of an object expressed in pounds, needs no conversion.

So if you relate that to the posting today what you find is this, some of the physics behind carrying the extra weight:

Example: m = 81 kg
g = 9.8 m/s^2
h = 0.608m (a two foot box jump)

Eg = mgh = (81kg x 9.8m/s^2) x 0.608m = 482.63 Joules of Gravitational PE

now say you lose 20 kilograms,

m = 61 kg
g= 9.8 m/s^2
h = 0.608m

Eg = mgh = (61kg x 9.8 m/s^2) x 0.608m = 363 Joules

That equates to using 24.78% less energy to perform the same task (one box jump)…thereby increasing fitness and reducing the strain on your body…!! Think about how many tasks you perform in a day and you can really begin to see the long term benefits of weight loss!!