4
5
fs=Ms N
Block A has mass 50 kg, Block B has mass 10 kg, and the coefficients of friction between all surfaces are 0.18
Static and 0.14 Dynamic.
If we started the assembly at rest at '0' degrees and slowly lifted it to an angle of theta, at what angle would
the blocks first start moving?
N=(M$_A$+M$_B$)gcos$\theta$
F=(M$_A$+M$_B$)gsin$\theta$
use f$_s$=f$_g$
M$_s$(M$_A$+M$_B$)gcos$\theta$=(M$_A$+M$_B$)gsin$\theta$
M$_s$gcos$\theta$=gsin$\theta$
M$_s$=\frac{gsin$\theta$}{gcos$\theta$}
M$_s$=tan$\theta$
$\theta$=tan$^{-1}$(.18)=$\theta$\rightarrow$\theta$=10.2$^\circ$
2
6
For the block problem above, if we started the problem instead at 30 deg (starting from rest releasing the
blocks), find a) the acceleration of block B and b) the tension in the cord.
