A car enters the freeway with a speed of 6.4 m/s and accelerates uniformly for 3.2 km in 3.5 min. How fast (in m/s) is the car moving after this time?

24.1 m/s

Explanation:

Using newton's equation of motion,

s = (v+u) t/2 ... Equation 1

Where s = distance, v = Final velocity, u = initial velocity, t = time.

making v the subject of the equation,

v = (2s/t) - u ... Equation 2

Given: s = 3.2 km = (3.2*1000) m = 3200 m, t = 3.5 min = (35 * 60) s = 210 s, u = 6.4 m/s.

substitute into equation 2

v = (2*3200/210) - 6.4

v = 24.076 m/s

v ≈ 24.1 m/s