Question

In a crash test, a car with a mass of 1600 kg is initially moving at a speed of 18 m/s just before it collides with a barrier. The final speed of the car after the collision is zero. The original length of the car is 3.80 m , but after the collision, the smashed car is only 3.23 m long

Answer 1

Concept:- we use kinematics equation to find acceleration first, then we find time during collision and considering that the compression of car is the distance travelled during collision we find speed,  

Concept: - we use kinematics equation to find acceleration first, then we find time during collision and considering that the compression of car is the distance travelled during collision we find speed, v_f^2 = v_i^2 + 2as v_f = 0, v_i = 18 m/s s = 3.8 m - 3.23 m = 0.57 m so, a = -284.2 m/s^2 v_f = v_i + at or, t = 0.0633 s so, v_avg = s/t = 0.57/t = 9 m/s t = 0.063 s - found aboveVertical-bar a Vertical-bar = 284.2 m/s^2 found above so, Vertical-bar f Vertical-bar = m Vertical-bar a Vertical-bar = (1600 kg) Vertical-bar a Vertical-bar = 4.547 times 10^5 N ��

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