Question #1411e

1 Answer
Apr 14, 2016

Answer:

So the answer is #d-> 3/2#

Explanation:

Tony B

Let clockwise be positive
Let anticlockwise be negative

Taking moments about #F_1# (Sum of moment must = 0)

#0=-(W/8xxL/16) -(F_2xx(5L)/8)+((5W)/8xx(5L)/16)+(W/4xx(6L)/8)#

#(5LF_2)/8= (25WL)/128+(3WL)/16-(WL)/128#

#(5LF_2)/8= (24WL)/128+(3WL)/16#

#(5LF_2)/8= (3WL)/8 #

#=>5LF_2=3WL#

#color(blue)(=>F_2=3/5W)#

'~~~~~~~~~~~~~~~~~~~~~~~~

#color(brown)("Total downward force = total up")#

#color(blue)(=>F_1=W-3/5 W = 2/5 W)#

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Thus the ratio of #F_1/F_2 = (2W)/5 -:(3W)/5 = 2/3#

So the answer is #d-> 2/3#