Mathematical query

[Desert Orchid]

This is for a friend who emailed me today (thinking I was a retired Maths teacher) to ask me:


I have been running around in the wifes old car, but am planning to buy a bigger one soon. I would like the long wheel base.

I'm unsure about my drive and garage. The old car scrapes its undercarriage when driving into garage with more weight than the wife and I in the front. A heavy suitcase in the boot with us both in the front and it just scrapes over the arch of the drive (entrance to garage), i have driven in with guests in the back and it seriously scraped the undercarriage.

I have attached a crap artistic effort of a side view of situation. (Can't copy it but the drive inclines up to meet the garage entrance at an angle.)

NEW CAR WHEEL BASE = 3157mm
OLD CAR WHEEL BASE = 2775mm

NEW CAR GROUND CLEARANCE = 120mm
OLD CAR GROUND CLEARANCE = 105mm

I haven't a clue how to work this out, and suspect it might be easier to know the exact angle of the entrance, but was 'hoping' there might be a way of comparing the two with those measurements by maybe converting them to percentages of each other or something (I wouldn't know how to go about getting the angle of the entrance, other than saying x distance out gives x amount of drop, but not sure how I could physically go about that task).
So my question boils down to, will an extra 15mm in ground clearance offset an extra 382mm in wheel base length?


I've said my gut says no as the ratio 38.2:1.5 looks to me like the scraping will be worse with the new car. Any ideas?

[simmo]

Tough one to say definitively, but I think you need to know how far along the car it is scraping at in order to create a picture of the two triangles which are being formed (one from the front wheels to the point of scraping and another from the point of scraping to the rear wheels).

You'd then be able to transpose the new measurements onto a replica to work out where it would scrape (if at all - I think it would be marginally better).

[trudij]

Surely the ground clearance is the issue rather than anything else? So if it’s that much higher it will be that much all round, so it would be ok?

Alternatively, tell him to let you know when he’s got the new car and found out


Sent from my iPhone using Tapatalk

[Desert Orchid]

[2017diary]

Maths question eh? Easy answer - just apply logic & ask for a test drive