In above question the retardation of rocket is:-

Explanation

To find the retardation of the rocket from the given velocity-time graph, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Graph**: The velocity-time graph shows two segments: one where the velocity is increasing (indicating acceleration) and another where the velocity is decreasing (indicating retardation).

2. **Identify the Points**: From the graph, identify the points where the velocity is maximum and where it starts to decrease. Let's assume the maximum velocity is at 1000 m/s and occurs at 120 seconds, while the velocity decreases to 0 m/s at 220 seconds.

3. **Calculate the Time Interval**: The time interval during which the rocket is undergoing retardation can be calculated as follows:
\[ \text{Time interval} = 220 \, \text{s} - 120 \, \text{s} = 100 \, \text{s} \]

4. **Calculate the Change in Velocity**: The change in velocity (from maximum to zero) is:
\[ \Delta v = 1000 \, \text{m/s} - 0 \, \text{m/s} = 1000 \, \text{m/s} \]

5. **Determine the Slope of the Graph**: The slope of the velocity-time graph represents the acceleration (or retardation). The formula for slope (retardation) is given by:
\[ \text{Slope} = \frac{\Delta v}{\Delta t} \]
Substituting the values:
\[ \text{Slope} = \frac{1000 \, \text{m/s}}{100 \, \text{s}} = 10 \, \text{m/s}^2 \]

6. **Identify Retardation**: Since we are dealing with retardation (negative acceleration), we express this as:
\[ \text{Retardation} = -10 \, \text{m/s}^2 \]

### Final Answer:
The retardation of the rocket is \( 10 \, \text{m/s}^2 \) (or \( -10 \, \text{m/s}^2 \) when considering direction).

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