# Stopping Distance + Reaction Time Problem ---> Physics beginner

by MyFinalRegret
Tags: beginner, distance, physics, reaction, stopping, time
 P: 2 1. The problem statement, all variables and given/known data A car is traveling at 80km/h, and brakes with a reaction time of .5 seconds. The car decelerates at 8m/s/s, determine the stopping distance of the car. 2. Relevant equations - V1 = V0 + at - D = V0t + 1/2at2 Where: V1 = Final Speed V0 = Initial Speed A = Acceleration T = Time D = Distance 3. The attempt at a solution Distance Traveled before Braking: 80km/h = 22.22m/s 0.5 * 22.22m/s = 11.11 m Distance After Reaction: V1 = V0 + at 0 = 22.22 - 8t t = 2.7775 seconds D = V0t + 1/2at2 D = 22.22 * 2.7775 - [(8 * 2.77752)/2] D = 30.86m Total Stopping Distance = 11.11m + 30.86m = 41.97 m Notes I am only beginning to learn some basic concepts of physics in class, so I'm not entirely sure about the equations. My teacher has provided no answer sheet to the question, and I am finding it hard to grasp the method of solving the question without a step by step example from a similar question. I'd greatly appreciate it if anyone could let me know if I am right, or how to do it if I am wrong. Thanks :D
 Mentor P: 40,276 Looks good to me--everything's correct. FYI, there's another kinematic equation that relates velocity and distance directly for accelerated motion. That would enable you to combine a few steps. See: Basic Equations of 1-D Kinematics
 P: 2 Thank you for the help and additional formulas ! Now I'll be able to do my other sums :D

 Related Discussions Introductory Physics Homework 9 Introductory Physics Homework 8 Introductory Physics Homework 2 Introductory Physics Homework 2 Introductory Physics Homework 4