How to find change in velocity and acceleration?

Question

A car moving 100 km/h (N) turns a corner and continues 100 km/h (W). The turn takes 0.025 seconds. How do i find the change in velocity and the acceleration?

Answer 1

Draw, from the same origin, vector v1 representing the velocity before turn, vector v2 representing the velocity after turn. The change in velocity  ÃŽÂ”v= v2 - v1 is represented by the vector joining the end of vector v1 to the end of vector v2

As v1 and v2 are perpendicular, the magnitude of vector Δv is

|Δv| = √(v1² +v2²) = √(100²+100²) = 100√2 = 141.424 km/h = 39.28 m/s

The average acceleration is:

a = |Δv|/Δt = 39.28/0.025 = 1571 m/s²

This acceleration is about 160 G, which is unsupportable even to a trained jet fighter super-pilot. So never drive 100 km/h and make a turn in only 0.025 sec.