Question

The force required to drag several objects across a floor was measured. Calculate the µK for these objects.





Block Weight Friction µK




A 150 lb 30 lb




B 20.0 N 5.0 N




C 1,500 lb 60 lb





(NOTE: I don't want want you to just give me the answer, I want to know how to work it.)

Answer 1

Answer:

Explanation:

Case-A

Block weight $W=150\ lb$

Friction Force $f=30\ lb$

and friction force is

$f=\mu _kN$

where N=normal reaction (Usually equals to weight)

$\mu _k=\frac{30}{150}$

$\mu _K=\frac{1}{5}=0.2$

Case-B

Block weight $W=20\ N$

Friction Force $f=5\ N$

$\mu _k=\frac{f}{N}$

$\mu _k=\frac{5}{20}=\frac{1}{4}$

$\mu _k=0.25$

Case-C

Block weight $W=1500\ lb$

Friction Force $f=60\ lb$

$\mu _k=\frac{f}{N}$

$\mu _k=\frac{60}{1500}$

$\mu _k=0.04$