A 1400 kg car is traveling at 24 m/s when the driver takes his foot off of the gas. The car eventually rolls to a stop after 225 m. What the force of friction acting on the car?

1 Answer
Feb 25, 2017

#1792N#

Explanation:

By Newton's second law, #F = ma#

In this case, the only force is friction.

So #F = 1400 * a#

Lets pause for a moment to find #a#.

Let's use one of the projectile motion equations. We choose this one because it has all the variable we know except for #a# so we can solve for #a#.

#V_f^2 = V_i^2 + 2ad#
#0 = 576 + 2*a*225#
#a = -1.28# (indicating the negative direction)

So back to our original equation:

#F = 1400 * a#
#F = 1400 * -1.28#
#F = 1400 * -1.28#
#=1792N# Opposite the direction of the movement of the car