A block of mass 4 kg is suspended through two light spring balances A and B is series. Then A and B will read respectively.

Options

A. `4kg` and zero kg
B. `4 kg` and `4kg`
C. zero kg and 4 kg
D. 2kg and 2kg

Explanation

To solve the problem of determining the readings of the two spring balances A and B when a block of mass 4 kg is suspended through them in series, we can follow these steps:

### Step 1: Understand the Setup
We have a block of mass \( m = 4 \, \text{kg} \) suspended by two light spring balances A and B in series. The total weight of the block will be acting downwards.

### Step 2: Calculate the Weight of the Block
The weight \( W \) of the block can be calculated using the formula:
\[ W = m \cdot g \]
where \( g \) is the acceleration due to gravity (approximately \( 9.8 \, \text{m/s}^2 \)). Therefore,
\[ W = 4 \, \text{kg} \cdot 9.8 \, \text{m/s}^2 = 39.2 \, \text{N} \]

### Step 3: Analyze the Forces Acting on the Balances
Since the balances are in series, the tension in the spring balances will be the same. The tension \( T \) in both balances will equal the weight of the block since they are supporting it.

### Step 4: Determine the Readings of the Balances
Both balances A and B will read the same value, which is equal to the weight of the block:
\[ T = W = 39.2 \, \text{N} \]

### Conclusion
The readings of the spring balances A and B will both be \( 39.2 \, \text{N} \).

### Summary of Readings
- Reading of Balance A = \( 39.2 \, \text{N} \)
- Reading of Balance B = \( 39.2 \, \text{N} \)

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