`45 km h^(-1)=` ______`ms^(-1)`

Options

A. 162
B. 12.5
C. 2.5
D. 75

Answer

To convert 45 km/h to m/s, we will follow these steps:

### Step 1: Understand the conversion factors
We know that:
- 1 kilometer (km) = 1000 meters (m)
- 1 hour (h) = 3600 seconds (s) (since 1 hour = 60 minutes and 1 minute = 60 seconds, thus 60 x 60 = 3600 seconds)

### Step 2: Set up the conversion
To convert kilometers per hour to meters per second, we can use the following relationship:
\[ \text{Velocity in m/s} = \text{Velocity in km/h} \times \frac{1000 \text{ m}}{1 \text{ km}} \times \frac{1 \text{ h}}{3600 \text{ s}} \]

### Step 3: Substitute the values
Substituting the given value of 45 km/h into the equation:
\[ \text{Velocity in m/s} = 45 \text{ km/h} \times \frac{1000 \text{ m}}{1 \text{ km}} \times \frac{1 \text{ h}}{3600 \text{ s}} \]

### Step 4: Simplify the expression
Now we simplify the expression:
\[ \text{Velocity in m/s} = 45 \times \frac{1000}{3600} \]

### Step 5: Calculate the result
Calculating the fraction:
\[ \frac{1000}{3600} = \frac{5}{18} \]
Now, substituting this back into the equation:
\[ \text{Velocity in m/s} = 45 \times \frac{5}{18} \]
Calculating this gives:
\[ \text{Velocity in m/s} = \frac{225}{18} = 12.5 \text{ m/s} \]

### Final Answer
Thus, \( 45 \text{ km/h} = 12.5 \text{ m/s} \).

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