Particle model suitable or not?

I would like to open a discussion on these two questions and what a persons thinking is to their answer?


Question is:

A car is modelled as a particle. Explain whether this is a suitable modelling assumption in these situations?

I. Finding how long the car takes to overtake a stationary van if length 6.2m

II. Finding how long the car takes to pass through a tunnel of length 380m

As I understand, a particle model is a suitable model where there’s no change of direction, hence something in a straight line. So, the position can be described as a single number from its starting point. If someone has more to add to this, please do.



Based on this, I suggested part I would be suitable, assuming the bus isn’t a round bus lol then the car would move in a straight line, there shouldn’t be a change of direction.

Part II. Due to the tunnel being extremely long, it would be harder to assume that it’s a straight tunnel and hence would be a change of direction, even slightly, therefore, wouldn’t be appropriate.

Any other opinions?

Here's an alternative interpretation.

i) I would say that overtaking starts when the front of the car first overlaps the van and finishes when the rear of the car no longer overlaps the van. The time needed to overtake the van will be significantly different for a car of length (say) 4.5m than for a particle of zero length.

ii) The tunnel is long compared with a car. Therefore the measured time for a car to pass through the tunnel will be about the same whether or not the length of the car is taken into account.

In that regards, it wouldn’t be suitable for the first but it would be the second.

Right, the results for passing though the tunnel wouldn’t differ much in terms of time, however, overtaking a parked car could should varied significant time differences and hence wouldn’t be suitable.