If she is driving at 20 m/s when suddenly she sees an obstacle in the road 50 m in front of her , the car will stop before it hits the obstacle.
<h3>Further explanation</h3>
Acceleration is rate of change of velocity.
<em>a = acceleration ( m/s² )</em>
<em>v = final velocity ( m/s )</em>
<em>u = initial velocity ( m/s )</em>
<em>t = time taken ( s )</em>
<em>d = distance ( m )</em>
Let us now tackle the problem!
<u>Given:</u>
Reaction Time = t' = 0.5 s
Acceleration = a = -6 m/s²
Initial Velocity = u = 20 m/s
Final Velocity = v = 0 m/s
<u>Unknown:</u>
Distance = d = ?
<u>Solution:</u>
When driver sees an obstacle , she has a reaction time of 0.5 s. It means that it takes 0.5 s before the car start to decelerate. We could calculate the car's distance during this time as shown below :
<h3 />
The time needed to slow down the car until it stops could be calculated as shown below :
The distance of the car during deceleration could be calculated as shown below :
At last , the total distance of the car from the moment the driver sees the obstacle is :
Total Distance is less than 50 m , therefore the car will stop before it hits the obstacle.
<h3>Learn more</h3>
<h3>Answer details</h3>
Grade: High School
Subject: Physics
Chapter: Kinematics
Keywords: Velocity , Driver , Car , Deceleration , Acceleration , Obstacle