Combined Variation
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Nanay GiCombined Variation
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Nanay GiThe maximum load m of a beam varies directly as the breadth b and the square of the depth d and
inversely as the length l. If a beam 3.6 m long, 1.2 wide, and 2.4 deep can safely bare a load up to
909 kg, find the maximum safe load for a beam of the same material which is 3 m long, 6 m wide
and 1.8 m deep.
: = . .
m = load
b = width / breadth
d = depths / height
l = length
m = 909 kg m = ? kg
b = 1.2 m b=6m
d = 2.4 m d = 1.8 m
l = 3.6 m l=3m
k=? k = 468.75 /2
(1.2 )(2.4 )2 468.75 /2 (1.2 )(1.8 )2
900 = =
3.6 3
1.2 (5.76 2 ) 468.75 /2 (1.2 )(3.24 2 )
900 = =
3.6 3
(6.912 3 ) 468.75 /2 (3.888 3 )
900 = =
3.6 3
900 (3.6 ) 468.75 /2 (3.888 3 )
= =
6.912 3 3
3,240 1,822.5 .
= =
6.912 2 3
= . / = . .