# Subject :- engineering mechanics ```SUBJECT :- ENGINEERING MECHANICS
PRESENTED BY
Dolly vyas
Branch EC 8TH SEM
&amp;technology
QUESTION
The smooth circular cylinders of figure each of
weight w = 100 N and radius r = 6 cm are
connected by string AB of length l = 16cm and
upon a horizontal plane, supporting a third
cylinder of weight Q3= 200 N and radius r =
6cm above them. Find the tension S in the
string AB and the pressure produced by the
floor at points of contact D and E ?
SOLUTION
Given :Two smooth cylinders weight (Q1,Q2) = 100 N
Radius of the all cylinders = 6 cm
String AB length = 16 cm
upper cylinder weight (Q3) = 200 N
Tension S in the string = ?
Pressure produced by the floor at points of contact
D and E = ?
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In this we use lami’s therom :-
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Now we find the value of Ra and Rb
For finding the value we make a free body diagram of cylinder Q3
By that we get the value of the angle between Rb and known weight
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And the angle between Ra and known weight
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And the angle between Ra and Rb
After that we get the value of
 Ra and Rb = 1.55 N
 This Ra and Rb are the tension S = 1.55 N
 Since both the smooth sylinder are in the point
contect of the surface so the value of the
pressure at the point contect will be
 Ra + Rb = weights of all cylinder
 Since Ra and Rb are equal so

2 Ra = 400 n