1. The problem statement, all variables and given/known data An extra-curricular theoretical assignment I have received: A car is travelling on a completely flat/uniform straight road at a constant velocity on a clear, dry day. 100 meters ahead, underneath the road there is a roller (similar to a rolling-road) which can spin without restriction (and assume without friction). The roller is the same width as the road and is laid perpendicular to the direction of travel so both front wheels will make contact with it at exactly the same time. Only 0.05m of the roller is exposed to the road - the rest is underground. The question is how will the car behave when it drives over the roller and which physical forces need to be considered when determining the behaviour. 2. Relevant equations NA 3. The attempt at a solution My thinking is the car should carry on and the roller will spin. The car may lose a little velocity but I'd be embarassed to submit this as an answer without backing it up. Which physical forces/equations do I need to consider to deliver an answer. Can anyone provide some guidance please? Thanks!