Question

A car accelerates from rest to a speed of 20 m/s in 10 seconds. What is its acceleration?

• A. 2 m/s²
• B. 3 m/s²
• C. 4 m/s²
• D. 5 m/s²

Hint:

Use the basic kinematic equation \( v = u + at \) to find acceleration when starting from rest.

Answer 1

The Correct Option is A

Step 1: Identify given values
- Initial velocity, \( u = 0 \, \text{m/s} \) (since the car starts from rest)
- Final velocity, \( v = 20 \, \text{m/s} \)
- Time, \( t = 10 \, \text{s} \)
- Acceleration, \( a = ? \, \text{m/s}^2 \)

Step 2: Select the appropriate kinematic equation
The first kinematic equation is: \[ v = u + at \] This equation relates initial velocity, final velocity, acceleration, and time, which matches our given data.

Step 3: Substitute values into the equation
Since \( u = 0 \): \[ v = 0 + at \implies v = at \] Substitute \( v = 20 \, \text{m/s} \) and \( t = 10 \, \text{s} \): \[ 20 = a \times 10 \]
Step 4: Solve for acceleration
\[ a = \frac{20}{10} = 2 \, \text{m/s}^2 \]