Question #872c3

1 Answer
Sep 21, 2017

Answer:

#a= 100m/s^2# deceleration
F= 100.000 N

Explanation:

using the two movement equations you have:
#S= v°t -1/2 at^2# and
# v= v°-at#
where v= 0 m/s (the car is stopped) V°= 20m/s . and acceleration has the opposite verse of velocity
From the second equation you have
# t= (V°)/a# that putting in the first equatin gives:# S= (V°^2)/a -1/2 (V°^2)/a =1/2 (V°^2)/a#
i.e
# 2m =1/2 (20m/s)^2/a#
then
#a= 100m/s^2#
from the second dinamic equation: F= ma we have #F= 1000 kg xx 100m/s^2= 100.000 N#