- I need to find the static and kinetic coefficient of a desk for a physics lab. we have pulleys, string, a scale, a "car" and a few other things. How would I find the force of friction?
I guess the desk and the floor.Friction involves two surfaces. What are they? Or do you mean rolling resistance?
The "scale" is as in a weighing scale?
What other things?
Which of all the items you listed can directly measure a force?I guess the desk and the floor.
scale is for weighing yes. things that can be used for weight (like paper, beads etc.), measuring tape and i think thats it but we are allowed to bring anything else we want.
by scale i mean bathroom scaleIf your 'scale' can measure tension in a string, just attach it to object(s) and pull - take reading at the point where the object(s) just begin to move. Alternatively increase slope of surface till object just begins to slide - then ##μ_s=tan(θ) ## if I remember correctly. I can't quite see how to do kinetic friction but I'd guess you will need some kind of 'ticker timer' experiment whereby the object(s) are pulled along the table surface by a falling weight of known value. You should be able to calculate coefficient of kinetic friction if you can obtain a value for the acceleration of falling mass and/or mass sliding on the table.
If you use weight in the right way, yes.would the weight which equals to force of gravity be equal to force Newton which is the same as force tension?