Posted by steve on Wednesday, January 26, 2011 at 11:27pm.
what is the formula to calculate the following:
how much force is needed to move a 10 pound block 10 feet in 8 seconds>

physics  drwls, Thursday, January 27, 2011 at 1:37am
Assuming there is no friction, proceed as follows.
The mass of the block is
M = W/g = 10/32.2 = 0.3106 slugs
Mass must be measured in slugs if you want the force in pounds, using Newton's second law.
The final velocity will have to be
2*10 ft/8 s = 2.5 ft/s to move 10 feet in 8 seconds. (The average velocity is half that, 1.25 ft/s)
The acceleration is
a = (2.5 ft/s)/8s = 0.3125 ft/s^2
Now use F = M a, with the mass M in slugs.
F = 0.097 pounds force
Look at it this way: You are accelerating the mass at about 1/100 g, so you need a force equal to only about 1/100 of the weight.