- #1

Liam C

- 57

- 4

## Homework Statement

A 1450-kg car is towing a trailer of mass 454-kg. The force of air resistance on both vehicles is 7471N[backward]. If the acceleration of both vehicles is 0.225m/s^2[forward], what is the force of static friction on the wheels from the ground?

## Homework Equations

Fnet = ma

Ff,s = UsFN (where Ff,s is the force of static friction, Us is the coefficient of static friction and FN is the force of the normal).

## The Attempt at a Solution

I know that since the tires are rolling, the force applied must be backward and the force of friction must be forward. As a result, the final answer should be positive.

Mc = 1450-kg, Mt =454-kg, FairR = 7471N[backward], a = 0.225m/s^2[forward], Δm = Mc + Mt, Ff,s = ?

Because of Newton's third law, I know that the applied force has a reactionary force pushing the car forward. As a result, the net force of the entire system(trailer and car) is:

Fnet = Δm x a

Fnet = (1450 + 454)(0.225)

Fnet = 428.4N [forward]

Given this, I think that I should find another equation for net force and then either solve for Ff,s or Us. I have tried this several times, but I can't seem to get it right. I would really appreciate some help as I have been stuck on this problem for hours.