14.8 A spring balance has a scale that reads from 0 to 50 kg. The length of the scale is 20 cm. A body suspended from this balance, when displaced and released, oscillates with a period of 0.6 s. What is the weight of the body?


Maximum mass that the scale can read, M = 50 kg
Maximum displacement of the spring=length of the scale, l=20 cm=0.2 m 
Time period, T=0.6 s
Maximum force exerted on the spring, F=Mg
 Where, g = acceleration due to gravity = 9.8 m/s2
 F=50×9.8=490 
Spring constant, k=Fl=4900.2=2450 Nm-1
Mass m, is suspended from the balance. 
Time period,  T=2πmk
m=T2π2×k=0.62×3.142×2450=22.36 kg
Weight of the body = mg = 22.36 × 9.8 = 219.167 N 
Hence, the weight of the body is about 219 N