Question

During a race, a runner runs at a speed of 6 m/s. Four seconds later, she is running at a speed of 14 m/s. What is the runner's

Answer 1

Answer:

D. 2 m/s²

Step-by-step explanation:

Initial speed of the runner (u) = 6 m/s

Final speed of the runner (v) = 14 m/s

Time taken (t) = 4 s

By using equation of motion, we get:

$\bf \longrightarrow v = u + at \\ \\ \rm \longrightarrow 14 = 6 + 4a \\ \\ \rm \longrightarrow 14 - 6 = 6 - 6 + 4a \\ \\ \rm \longrightarrow 8 = 4a \\ \\ \rm \longrightarrow 4a = 8 \\ \\ \rm \longrightarrow \dfrac{4a}{4} = \dfrac{8}{4} \\ \\ \rm \longrightarrow a = 2 \: m {s}^{ - 2}$

$\therefore$ Acceleration of the runner (a) = 2 m/s²