A car starts from rest and covers a distance of 40 m in 10 s. Calculate the magnitude of its acceleration

1. Analyze the Question

We are given the following information about a car's motion:

• Initial velocity ($u$) = $0 \text{ ms}^{-1}$ (since it starts from rest)
• Distance covered ($s$) = $40 \text{ m}$
• Time taken ($t$) = $10 \text{ s}$
• We need to find the acceleration ($a$).

2. Explain the Concept

To solve this, we use the equations of uniformly accelerated motion. Specifically, the second equation of motion relates distance, initial velocity, time, and acceleration:

Where:

• $s$ is the distance
• $u$ is the initial velocity
• $t$ is the time
• $a$ is the acceleration

3. Show the Solution

Step 1: Substitute the known values into the formula.

Step 2: Simplify the equation. Since $0 \times 10 = 0$:

Step 3: Solve for $a$.

4. Identify the Answer

Comparing our result to the given options: A. 3.20 ms$^{-2}$ B. 0.25 ms$^{-2}$ C. 0.80 ms$^{-2}$ D. 4.00 ms$^{-2}$

The calculated value matches Option C.

5. Exam Tip

Whenever you see the phrase "starts from rest," immediately note that $u = 0$. This simplifies your equations significantly because the $ut$ term disappears, leaving you with just $s = \frac{1}{2}at^2$. This is a common shortcut in JAMB Physics to save you time!