A car moves with an initial velocity of 25 ms$^{-1}$ and reaches a velocity of 45 ms$^{-1}$ in 10s. What is the acceleration of the car?

Analyze the question: The car speeds up from 25 m/s to 45 m/s over 10 s. We need its acceleration, which is the rate of change of velocity.

Concept: Acceleration is the change in velocity divided by the time taken:

a = (v − u) / t

where u is the initial velocity, v is the final velocity and t is the time.

Solution:

• u = 25 m/s
• v = 45 m/s
• t = 10 s

a = (45 − 25) / 10 a = 20 / 10 a = 2 m/s²

Answer: The acceleration is 2 ms⁻², which is option A.

Tip: Always subtract the initial velocity from the final velocity before dividing by time. A common mistake is to divide 45 or 25 by 10 directly. Also check your units: m/s divided by s gives m/s².