A body starting from rest has an acceleration of `5m//s^(2)`. Calculate the distance travelled by it in `4^(th)` second.

Explanation

To solve the problem of calculating the distance traveled by a body in the 4th second, we can use the formula for the distance traveled in the nth second of motion. Here’s the step-by-step solution:

### Step 1: Identify the given values
- Initial velocity (u) = 0 m/s (since the body starts from rest)
- Acceleration (a) = 5 m/s²
- n (the nth second) = 4

### Step 2: Use the formula for distance traveled in the nth second
The formula to calculate the distance traveled in the nth second is given by:

\[ d_n = u + \frac{a}{2} (2n - 1) \]

### Step 3: Substitute the values into the formula
Now, we can substitute the values into the formula:

\[ d_4 = 0 + \frac{5}{2} (2 \times 4 - 1) \]

### Step 4: Simplify the expression
Calculate \(2 \times 4 - 1\):

\[ 2 \times 4 - 1 = 8 - 1 = 7 \]

Now substitute this back into the equation:

\[ d_4 = \frac{5}{2} \times 7 \]

### Step 5: Calculate the final distance
Now calculate \(\frac{5}{2} \times 7\):

\[ d_4 = \frac{35}{2} = 17.5 \text{ m} \]

### Conclusion
The distance traveled by the body in the 4th second is **17.5 meters**.

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