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Standard X

Physics

Static Equilibrium

A 4 m long ro...

Question

A 4 m long rod of negligible weight is supported at a point 125 cm from its one end and a load of 18 kgf is suspended at a point 60 cm from the support on the shorter arm.

(a) if a weight W is placed at a distance of 250 cm from the support on the longer arm, find W.

(b) If a weight 5 kgf is kept to balance the rod, find the position.

(c) To which class of lever does it belong?

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Solution

Total length of rod = 4 m = 400 cm

(a) 15 kgf load is placed at 60 cm from the support.

W kgf weight is placed at 250 cm from the support.

By the principle of moments,

$18 \times 60 = W \times 250 W = 4.32 k g f$

(b) Given W = 5 kgf

18 kgf load is placed at 60 cm from the support.

Let 5 kgf is placed at d cm from the support.

By the principle of moments,

$18 \times 60 = 5 \times d d = 216 c m$

d = 216 cm from the support on the long arm.

(c) It belongs to the class I lever.

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