Change a speed of 12 m/sec into km/hr.

Answer

To convert a speed of 12 meters per second (m/sec) into kilometers per hour (km/hr), we can follow these steps:

### Step 1: Understand the conversion factors
1. **Conversion from meters to kilometers**:
- 1 kilometer (km) = 1000 meters (m)
- Therefore, 1 meter = \( \frac{1}{1000} \) kilometers.

2. **Conversion from seconds to hours**:
- 1 hour = 60 minutes
- 1 minute = 60 seconds
- Therefore, 1 hour = \( 60 \times 60 = 3600 \) seconds.
- Thus, 1 second = \( \frac{1}{3600} \) hours.

### Step 2: Set up the conversion
We need to convert 12 m/sec into km/hr. We can use the conversion factors we found in Step 1.

### Step 3: Apply the conversion
Using the conversion factors:
\[ \text{Speed in km/hr} = \text{Speed in m/sec} \times \left(\frac{1 \text{ km}}{1000 \text{ m}}\right) \times \left(\frac{3600 \text{ sec}}{1 \text{ hr}}\right) \]
Substituting the values:
\[ \text{Speed in km/hr} = 12 \times \left(\frac{1}{1000}\right) \times 3600 \]

### Step 4: Simplify the expression
\[ \text{Speed in km/hr} = 12 \times \frac{3600}{1000} \]
\[ \text{Speed in km/hr} = 12 \times 3.6 \]

### Step 5: Calculate the final result
\[ \text{Speed in km/hr} = 43.2 \text{ km/hr} \]

Thus, the speed of 12 m/sec is equivalent to **43.2 km/hr**.

---