Originally Posted by JoeyO
There's different frictional dynamics associated with "push" verses "pull". A 15' long wooden 2 x 4 will want to wiggle and squirm more when pushed up an incline, verses pulling it up an incline.
We are note trying to get the car up the hill sliding up its belly with no wheels. Put some widely spaced wheels on that board and it is happy being pushed.
In fact, you then have a skate board - they work great pushed.