# Formula for work & Time ?

by momentum
Tags: formula, time, work
 Sci Advisor PF Gold P: 1,382 The simplest formula for mechanical work (in Physics) is $$W = F s$$ Here, the force is contant and parallel to displacement and the body moves in a steady direction. W is work, F is force and s is displacement. The result is in Joules. Unless you want manhours? What exactly are you trying to do? :)
 Mentor P: 41,454 Formula for work & Time ? $$N_1 R D_1 = W = N_2 R D_2$$ Where: N = number of men; R = rate of work done per man (assumed constant); D = days (or time); W = total work done.
 Mentor P: 41,454 Don't treat this as some esoteric formula from the ancients. It should be just "common sense", a variation of "Distance = Rate X time". An example of R would be: a man can lift 50 bales of hay per day, so R = 50 bales/day/man. So, if one man can lift 50 per day, how much total can be lifted in 3 days by 5 men? Using W = N R D gives, W(total) = (5 men) (50 bales/day/man) (3 days) = 750 bales But to solve a problem like " if 20 men working 10 days did a certain amount of work, how long would it take 30 men to do the same work?" you don't have to know R. Just use: $$N_1 R D_1 = W = N_2 R D_2$$ (20)(R)(10) = (30)(R)($D_2$) Note that the Rs just drop out, and $D_2$ = 20/3 days.