Question

4. A uniform metre scale rests horizontally on a knife edge
at the 60 cm mark when a mass of 10 g is suspended
from one end. At which end this mass be suspended.
What is the mass of the metre scale?
(Ans. towards the 100 cm mark, 40 g)
​

Answer 1

toward 100 cm to balance the scale

concept of center of mass

now let the mass of scale m per cm

on left side the mass is 60m

on right side mass is 10+40m

60m=10+40m

20m=10

m=0.5g per cm

total weight of scale is 0.5×100

50g