Force and Power

[Jowan]

From another thread:
AHHHHHHHHH this if p**sing me off now!
force = mass x acceleration, well the human body's mass can't come into effect, what if they were on the ground doing say a bench press, their mass would not come into it, it would be only how strong their muscles were!
can someone give me a seriously exact definition, using scientific equations, but explaining them in detail, not taking anything for granted, the bits i cannot understand are where the acceleration comes from in the force equation, bloody helli have thought for a hour now and i cant get my head round it.
please someone explain this...
explain what force is, how it is used in the human body, what 'power' is, how it is used in the human body, and for the last time- how these effect people!
-Jowan-

[Szczepankiewicz]

If you can form your rambling into coherent questions I'm sure someone can answer them for you.

[Jowan]

Not many people will speak coherently, but sometimes if you want the greater go9od you have ot ignore the excuse 'i cant understand' and just try.
-Jowan-

[Szczepankiewicz]

I can't argue with that...

[Jowan]

[eXcessiveForce]

I will try to help but am somewhat pressed for time.


Velocity is a constant speed. A car driving for an hour at 55miles per hour could be said to have a velocity of 55.

Acceleration is the change in velocity over time.
A car goes from 0 to 60 in 4 seconds. That is acceleration. It's speed varies though out those 4 seconds. Initial acceleration would be 0. it is measured over time.

So if you start a punch it would start at 0 acceleration. As muscles contract movement of the limb is begun. This creates the acceleration. If it reaches maximum acceleration before it strikes the target it would be called velocity.

Mass does come from the body, getting your weight behind your punch. "don't move your body, just your arm and throw a punch. Very low mass, only the mass of the arm. very low force, or power." Now throw a correct punch from the legs and hip movemnt and shoulder movement,. Hit the target. The mass of the body is now moving forward into the punch. More mass more force.


If you want to think of it more simply then you need to understand the concept of vectors. Think of vectors like arrows drawn on paper. A vector's arrow varies to the amount of force.
Vectors can combine to create larger arrows (more force)

now think of a punch again. The first Vector would be a small arcing arrow as the back foot shifts. Next it would combine with the vector(arrow) from the extension of the back leg. Since the first arrow is curved and the second straight there is some loss of energy so if the first arrow is 10 units and the second arrow is 30 units. You won't get 40 units but more like 37 units. The next vector is the hip turning, another curved arrow, then the body leaning forward is a vector, then the shoulder rotation, the the arm rotation. then the wrist rotation.

now. The more vectors you add that move in similar directions the more force you will have. Arrows that run opposite cancel out. so 10 units forward and 10 units backwards out equal 0.
no force.

When you jump Gravity pulls down at 10 meters per second.

So if you jump from your starting point up at 10 meters a second you must use 20 unites to move upward at 10 meters a second.


Lifting weights uses different equations that the one you asked about.

[Turing]

When you jump gravity pulls you down at 9.8 meters per second, per second. That is to say after one second you are moving down at 9.8 meters per second, but after 2 seconds of free fall you are moving at 19.6 etc.