How much pressure should be applied on a litre of water if it is to be compressed by 0.1%?
(Bulk modulus of water= 2100 MPa)

Options

A. 2100 kPa
B. 210 kPa
C. 2100 Mpa
D. 210MPa

Explanation

To solve the question of how much pressure should be applied on a litre of water to compress it by 0.1%, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Given Data**:
- Bulk modulus of water, \( K = 2100 \, \text{MPa} = 2100 \times 10^6 \, \text{Pa} \)
- Compression percentage, \( \Delta V / V = 0.1\% = 0.1 / 100 = 0.001 = 10^{-3} \)

2. **Understand the Formula for Bulk Modulus**:
- The bulk modulus \( K \) is defined as:
\[ K = -\frac{P}{\Delta V / V} \]
- Rearranging this formula gives us:
\[ P = K \times \left(-\frac{\Delta V}{V}\right) \]
- Since we are dealing with compression, we can drop the negative sign for pressure calculation.

3. **Substitute Values into the Formula**:
- Plugging in the values we have:
\[ P = K \times \left(\frac{\Delta V}{V}\right) = 2100 \times 10^6 \, \text{Pa} \times 10^{-3} \]

4. **Calculate the Pressure**:
- Performing the multiplication:
\[ P = 2100 \times 10^6 \times 10^{-3} = 2100 \times 10^3 \, \text{Pa} = 2100 \, \text{kPa} \]

5. **Final Answer**:
- Therefore, the pressure that should be applied on a litre of water to compress it by 0.1% is:
\[ \boxed{2100 \, \text{kPa}} \]