Question

6) A Honda Fit is initially with a speed of 115 km/h. Find its acceleration and the time taken to stop given that: (a) it brakes to a stop in 64.0 m: (b) it crashes head-on into a barrier andI crumples by 1.00 m

Answer 1

Given speed = u = 115km/h = 31.94m/s a) using the Kinematics equation u^2 - v^2 = 2as 0 - (31.94)^2 = 2a (64) a = 7.97 m/s^2 Again using the Kinematics equation s = ut + 1/2 a t^2 64 = (31.94) t + 1/2 (7.97)t^2 64 = 31.94 t + 3.985 t^2 3.985 t^2 + 31.94 t - 64 = 0 By solving the equation t = 1.65997 s = 1.66 s b) Using the Kinematics equation u^2 - v^2 = 2 a s 0 - (31.94)^2 = 2 a (1) a = 510.08 m/s^2 Using the kinematics equation s = u t + 1/2 a t^2 1 = (31.94) t + 1/2 (510.08) t^2 1 = 31.94 t + 255.04 t^2 1 = 31.94 t + 255.04 t^2 255.04 t^2 + 31.94 t - 1 = 0 By solving the equation t = 0.025937 s = 0.026 s