Question

a car starts from rest at a stop light and reaches 20 m/s in 3.5 s. determine the acceleration of the
7.0m/s²
5.7m/s²
2.2m/s²
70m/s²

Explanation:

Step1: Recall acceleration formula

Acceleration \( a \) is given by the change in velocity \( \Delta v \) over time \( \Delta t \), so \( a=\frac{\Delta v}{\Delta t} \).

Step2: Identify initial and final velocity

Initial velocity \( v_0 = 0\,\text{m/s} \) (starts from rest), final velocity \( v = 20\,\text{m/s} \), time \( t = 3.5\,\text{s} \).

Step3: Calculate change in velocity

\( \Delta v=v - v_0=20 - 0 = 20\,\text{m/s} \).

Step4: Compute acceleration

\( a=\frac{20}{3.5}\approx5.7\,\text{m/s}^2 \).

Answer:

5.7 m/s² (corresponding to the purple option: 5.7m/s²)