Two identical spring balances S1 and S2 are connected one after the other and are held vertically as shown in the figure. A mass of 10 kg is hanging from S2. If the readings on S1 and S2 are W1 and W2 respectively, then :

When two spring balances are connected in series (one after the other) and a weight is suspended from the bottom balance, the tension created by the weight is transmitted equally through both balances.

• Balance S2: It directly supports the 10 kg mass. Therefore, the downward force (weight) acting on it results in a reading of W2 = 10 kg.
• Balance S1: It supports balance S2 and the 10 kg mass. In ideal physics problems where the mass of the spring balances themselves is considered negligible, the tension remains constant throughout the vertical chain. Thus, S1 experiences the same downward pull of 10 kg, leading to a reading of W1 = 10 kg.

Since the weight is transmitted through the entire system, both identical spring balances will show the same reading of 10 kg. Hence, Option D is correct.