# Simple Work

can anyone help me out with a simple work problem?

say I lifted a bag of shingles that weighed 90 lbs from the ground to 6 feet in 5 seconds, then took 8 seconds to walk that bag to a scaffold which upon arriving to the scaffold it took me an aditional 3 seconds to put it from my 6 foot shoulder to the 6'6" scaffolding platform.

how much work would be involved?

(note: assume there is no aditional forces work on any part such as friction or wind)

## Answers and Replies

Jonathan
I think the first part is 108 ft*lb/s and the second is 15 ft*lb/s, but I can't be sure because I get confused when not using metric, and I can't ever remember any conversions except for 2.54cm=1inch.

Staff Emeritus
Gold Member
Work is force times distance. Time does not matter. Pounds is a unit of force so 90lb*6.5ft. The only distance that counts is change in elevation.

Jonathan
YES

That makes much more sense, I was thinking power or something. Foucoso mentioned time, so maybe he meant to ask for the power not work though.

err, yeah. i meant energy used. i only refered to it as a work problem because that is what i did at work.

Staff Emeritus