The speed of the vehicle before the brake were applied was about 80 feet/s
Acceleration is rate of change of velocity.
[tex]\large {\boxed {a = \frac{v - u}{t} } }[/tex]
[tex]\large {\boxed {d = \frac{v + u}{2}~t } }[/tex]
a = acceleration ( m/s² )
v = final velocity ( m/s )
u = initial velocity ( m/s )
t = time taken ( s )
d = distance ( m )
Let us now tackle the problem!
This problem is about Deceleration
Given:
final speed = v = 0 m/s
length of skid marks = d = 175 feet
maximum deceleration = a = 20 feet/s² ( assumption )
Unknown:
initial speed = u = ?
Solution:
We will solve this problem by using following formula:
[tex]v^2 = u^2 - 2ad[/tex]
[tex]0^2 = u^2 - 2(20)(175)[/tex]
[tex]u^2 = 7000[/tex]
[tex]u = \sqrt{7000}[/tex]
[tex]u = 10\sqrt{70} \texttt{ feet/s}[/tex]
[tex]u \approx 80 \texttt{ feet/s} [/tex]
Grade: High School
Subject: Physics
Chapter: Kinematics
Keywords: Velocity , Driver , Car , Deceleration , Acceleration , Obstacle , Braking , Deceleration , Skid Marks
