Question

a driver takes 0.30 seconds to apply the brakes. if he is driving car at a speed of 72km/hr and the brakes cause a deacceleration of 5.0m/sec. fimd the distance tavelled by the car after he sees the need to put brakes

Answer 1

so distance covered is S1 = v.t = 20.83*0.2 = 4.16 mts it moves with constant deceleration of -5 m/sec2 and initial speed of 20.83m/secUsing relation V2 - u2 = 2*(-a)*SS2 = V2/2*a = 20.83*20.83/(2*5) = 433.889/10 =43.39 mtsthe distance travelled by car after he sees need to put brakes is S1+S2 = 47.55 mts