Hello, I have a thought. Work:Fd I think is proportional to Work:Ft because distance and time are proportional. So, is correct to say that work is W:Ft?

Question

anonymous · Answer

Well, Actually both aren´t propotional, because several forces can be projected in a body so a force can lasts an hour and the body wont move. They are propottional only when there´s only one force projected in the body.

anonymous · Answer

Even if there is only one force, and it is constant, then the body would have an acceleration (F = ma). So actually, since the distance in this case is $$s = v_{0} + 1/2at ^{2}$$ they aren't directly proportional in that way. Note that there also might be several forces which could be non-constant over the time interval t.

For these reasons, it usually isn't the best way to use the energy approach when it comes to problems including time.

anonymous · Answer

Okey, I was thinking that the distance that a body moves because of a force is proportional to the duration of that force.
 
The distance that a body moves, is d:(V2 - V1)/2; if taking a reference system that makes V1 always 0 the the distance is V2/2. Now V2:At. Velocity 2 is proportional to the acceleration per second and the time that the force lasts. So, d: (At)/2.

That´s why I said that the distance that a body moves because of a force  is proportional to the duration of that force.

anonymous · Answer

No.  Simply because the units don't make sense.  Force = [M][L][T^-2] which is mass x acceleration, then multiplying by a distance gives  [M][L^2][T^-2] which are the units of energy.  Force x time would give [M][L][T^-1] which is not energy but momentum.  M = mass, L = length, T = time. (usually in kg, m and s).  Always make sure your units work out and that will help you decide if you are on the right tracks.

anonymous · Answer

You know, I´m just saying that both are proportional when theres only one force acting. Is like when you said that distance equals times squared when a body is falling to the to a gravity field. Even if the units are differents, there´s a relation.

anonymous · Answer

force is acting on an object to move it . thus work is propotional to force * distance moved. but time period of force which is exerted on an object is to change its inertia of static to dynamic.