posted by anonymous .
a car of mass 900 kg moves at 10 m/s. what is the braking force required to stop the car in a time of 5 seconds?
Find the required acceleration.
a = (Vf-Vi)/t
where Vf = final velocity and Vi = initial velocity
You want final velocity to be 0.
a = (0-10)/5
a = -2 m/s/s
Now to find the force:
F = ma
F = 900*-2
F = -1800N
The force required is 1800N applied opposite from the direction of motion.