# Trailer FBD

1. Mar 11, 2016

### theone

1. The problem statement, all variables and given/known data
The context of this problem involves a dolly pulling a trailer, and I am trying to establish the basic free body diagram for the trailer. Is what is done so far acceptable and is this a step in the right direction?

2. Relevant equations

3. The attempt at a solution
I am confident about the vertical forces, but can't gather what forces are opposing horizontal motion.

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2. Mar 11, 2016

### SteamKing

Staff Emeritus
Well, it's a trailer. You don't want too many forces opposing horizontal motion, otherwise you're dragging the thing along.

Think about where the trailer makes contact with the ground. What forces are present there?

3. Mar 14, 2016

### theone

is it just the vertical contact forces between the tire/ground and the trailer tongue/ground as well as the horizontal friction force from the tires?

The full question involves the design of a dolly for the trailer. So when the dolly is connected to the trailer, should that just be taken as reaction forces Ax, Ay?