If I have a 400lbg weight , and I need to pull it 1 meter , and it takes me 1.5 seconds to pull it . How much force am I using ? ... Do I need to use kinetic energy formula ? Or just the regular force =ma/m^2??

Question

ljetibo · Answer

that's a weird looking "regular" force. The one I know about looks like F=ma.
I suggest you take a peak at momentum and/or impulse to solve this task.
$$F \Delta t = \Delta p$$

vegamontiel · Answer

So what equation would you suggest I use ?? Because I have all the numbers and weights . I'm just not sure what equation to use .

vegamontiel · Answer

Because I think I also need to include natural force of gravity right ??? An direction ?

ljetibo · Answer

Let's say you've raised the weight 1m up. Then the change in gravitational potential energy is 
Epot = mgh = 181.436948kg * 9.81 * 1 = 1778.0820904000002 Joules
that is to say that you've done ~1780Joules of work. You've done it in 1.5 seconds:
 P=W/t = F*h/t = 1185.38806027Watts 
so it's been done by using 1185.4 Watts of Power. On average you've pulled it with the force of:
F = t*1185/h = 1.5*1185/1 = 1177N
which means that 
Ft = mv -> v = Ft/m = 9.7272727 m/s 
or that you've accelerated this object from 0 to ~10m/s in a span of a second and a half.