Question

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

1. If a weight W is placed at a distance of 250 cm from the support on the longer arm to balance the rod, find W.
2. If a weight 5 kgf is kept to balance the rod, find its position.
3. To which class of lever does it belong?

Answer 1

(a) W × CE = 18 × DC

W × 250 = 18 × 60

∴ W = `(18 xx 60)/250`

∴ W = 4.32 kgf

(b) New W = 5 kgf

Let it be placed at a distance x from C on arm CB

∴ 5 × x = 18 × 60

∴ x = `(18 xx 60)/5`

= 216 cm = 2.16 m

(c) It belongs to class I lever.