A bus moving along a straight line at 20 m/s undergoes an acceleration of 4 m/`s^(2)`. After 2 seconds, its speed will be :

Options

A. 8 m/s
B. 12 m/s
C. 16 m/s
D. 28 m/s

Answer

To solve the problem, we will use the first equation of motion, which relates the final velocity (v), initial velocity (u), acceleration (a), and time (t). The equation is given by:

\[ v = u + a \cdot t \]

### Step-by-step Solution:

1. **Identify the given values:**
- Initial velocity (u) = 20 m/s
- Acceleration (a) = 4 m/s²
- Time (t) = 2 seconds

2. **Substitute the values into the equation:**
\[ v = u + a \cdot t \]
\[ v = 20 \, \text{m/s} + (4 \, \text{m/s}^2 \cdot 2 \, \text{s}) \]

3. **Calculate the product of acceleration and time:**
\[ 4 \, \text{m/s}^2 \cdot 2 \, \text{s} = 8 \, \text{m/s} \]

4. **Add this value to the initial velocity:**
\[ v = 20 \, \text{m/s} + 8 \, \text{m/s} = 28 \, \text{m/s} \]

5. **Conclusion:**
The final speed of the bus after 2 seconds is **28 m/s**.