Question

A driver spotted a police car and he braked from a speed of 100 km/h to a speed of 80 km/h during a displacement of 88 m at a constant acceleration? What is that acceleration, and how much time is required for the given decrease in speed?​

Answer 1

Answer:

Explanation:

100 kph = 27.8 m/s

80 kph = 22.2 m/s

v² = u² + 2as

a = (v² - u²) / 2s

a = (22.2² - 27.8²) / (2(88))

a = -1.578282828...

a = -1.58 m/s²

t negative sign means the acceleration opposes the initial velocity.

t = Δv/a

t = (22.2 - 27.8) / -1.57828

t = 3.52 s