Question

a uniform metre scale balances at 40 cm mark when weights of 10g and 20g are suspended from 10 cm and 20 cm marks. the weight of the metre scale is

Answer 1

0 cm--------10cm--------20cm----------40cm------50cm-----------------------------100cm

                10g              20g               !!!!!             w

sum of moments anti clockwise=100+400

sum of moments clockwise=50*w

by principal of moments

sum of clockwise moments=sum of anti-clockwise moments

=>50*w=500

=>w=10 grams

therefore weight of the meter scale is 10 grams