Lifting mass fast or slow?

Question

Hey,

When lifting a mass, is it more efficient to lift it fast or slow? or is it exactly the same?

I think its exactly the same, but not sure how i should go about proving it.

Thanks very much

Answer 1

Assuming there is no loss of energy due to the method of lifting the mass, the same amount of energy must be expended regardless of how long it takes. The reason is that the potential energy depends only on the height:

P.E. = mgh

Answer 2

This is a tricky question with no clear-cut right answer.  It depends on the mechanism you're using to lift the mass.

If a human lifted a 10-pound object 5 feet vertically in 2 seconds, they would likely be relatively efficient.  However, if they lifted the same 10-pound object 5 feet vertically in 20 minutes, they would expend a great deal of energy just holding the thing in place; far more than they'd use increasing the potential energy of the object.  So, for a human lifting small objects, faster is more efficient (up to a point).

Answer 3

its da same

ur muscles undergoes  da same force, thus doesnt really make a difff...

Answer 4

It is not the velocity, it is the acceleration

Newtons low: F(total)=m*a

When you lift the body:

F-W=m*a

F=W+m*a

If the acceleration is zero F=W

so you need minimum force

As for the energy and velocity

If you lift the mass, you will need energy

E=U+K

E=m*g*h+.5*m*v^2

If v is max then E is max

If v is min then E is min