# Homework Help: Homework Porblem - Forces

1. Feb 12, 2008

### aalsaigh

Homework Porblem -- Forces

1. The problem statement, all variables and given/known data

A tractor with two trailers moves at a constant speed on a straight level road. The mass of the tractor is 5000 kg and the mass of each trailer is 25 000 kg.
a) Determine the force exerted by each of the two trailer hitches.
b) Repeat, if the tractor-trailer is acceleration at 2 m/s^2
c) Repeat, if the coefficient of friction is 0.7

2. Relevant equations

F friction = (coeff of friction)(F normal)
F net = ma
F g = mg

3. The attempt at a solution

a) 0
b) a = 2 m/s^2. F = ma
First one = ma = (50 000)(2) = 100 000 N
Second = ma = (25 000)(2) = 50 000 N
c) I don't know how to go about this, but I did find F g for each trailer.
last trailer: Fg = mg = 245 000
Second one: Fg = 245 000
F friction = (0.7)(245 000) = 171 500

That's as far as I got.

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