[wolfgang]

Someone stole a truck and wanted to cross the border with it,there is a (one way) tunnel as a short way to the border.

As he was 150 yards away from the tunnel he parked a side because he noticed that there was no traffic sign indicating the height of the tunnel ,moreover he knows nothing about the height of the truck.

If he take a risk and drive,the truck may stuck if the tunnel is too low( he can not drive backwards).

How can he make a rough estimation to know whether this truck can pass through that tunnel or not?

Note : he didn`t have any measuring tools.

( he smoke marlboro...)

[Guest]

He can light a cigarette and measure how much time it takes the smoke to rise to the height of the truck and the height of the tunnel. If the smoke takes longer to reach the ceiling of the tunnel, chances are the truck is shorter.

Of course, he has to hope there aren't any rogue updrafts or strong winds to affect the rise of the smoke.

[wolfgang]

He can light a cigarette and measure how much time it takes the smoke to rise to the height of the truck and the height of the tunnel. If the smoke takes longer to reach the ceiling of the tunnel, chances are the truck is shorter.

Of course, he has to hope there aren't any rogue updrafts or strong winds to affect the rise of the smoke.

nope...

[Guest]

Walk to middle point, 75 yards, between truck and tunnel. Hold a cig at arms length. Use it to measure height of truck. Now turn 180 and measure height of tunnel. If its close, just let some air out of the tires.

[Guest]

Walk to middle point, 75 yards, between truck and tunnel. Hold a cig at arms length. Use it to measure height of truck. Now turn 180 and measure height of tunnel. If its close, just let some air out of the tires.

smart.

[Guest]

An unsmoked Marlboro cigarette is 85 millimeters in length. The distance to the tunnel is 150 yards. By a quick conversion of measures (the cigarette being approximately 0.0929513 yards in length), and using trigonometic calculations from the estimated measures taken using of the cigarette as a miniature surveyor's Jacob's staff, the thief can calculate the heights of the tunnel and the truck, thereby determining if the tunnel is the route he should take.

Edited June 28, 2011 by Dej Mar

[Guest]

Solow and Dej Mar make the assumption that the 150 yards is correct.

To get trucks height, mark truck even with top of head and walk a short distance, then, using a cigarette at arms length, determine relative truck height to his height. Knowing how tall he is, can calculate truck height. Now do the same for the tunnel.

[Guest]

Flag down a vehicle with someone with a tape measure. Tell them "I will give you this cigarette if you tell me how tall the tunnel and my truck are."

But, why not just drive to the tunnel. If you can pass through, so be it. If you get stuck, you have just plugged the hole and the police can't follow you. Just hop out and leisurely stroll to freedom.

[Guest]

Solow and Dej Mar make the assumption that the 150 yards is correct.

To get trucks height, mark truck even with top of head and walk a short distance, then, using a cigarette at arms length, determine relative truck height to his height. Knowing how tall he is, can calculate truck height. Now do the same for the tunnel.

The 150 yards cited is not just a simple assumption, but a given.

[Guest]

The solution I came up with is similar to Cheesner's solution. Stand next to the highest point on the truck, and hold the cig at arms length. Mark the height of the tunnel on the cig with your finger nail. Walk to the tunnel entrance and check the height of the truck against the mark on the cig. This is a twist on a basic artist technique for keeping things to scale.

You are given no way to accurately find the midpoint. So with Cheesner's solution, if you are off from the midpoint, your results will be off.

I don't smoke, but I doubt the exact length of a cig is common knowledge. Dej Mar's calculation method wouldn't work if the cig's length was unknown.

[benjer3]

I like quever's more than mine, but the first thing I thought of, ignoring the Malboro hint, was...

Wait for a time of day when the sun is shining into the tunnel (a north-facing tunnel won't work for this) and then pace off from the entrance of the tunnel to where the shadow starts and from the front of the truck's trailer to the end of the trailer's shadow. If the shadows are too small, he could even use the cigarette. If there is more light in the tunnel than shadow from the truck, he can get through.

Edited June 29, 2011 by benjer3

[wolfgang]

Walk to middle point, 75 yards, between truck and tunnel. Hold a cig at arms length. Use it to measure height of truck. Now turn 180 and measure height of tunnel. If its close, just let some air out of the tires.

Very good!!!

[wolfgang]

The solution I came up with is similar to Cheesner's solution. Stand next to the highest point on the truck, and hold the cig at arms length. Mark the height of the tunnel on the cig with your finger nail. Walk to the tunnel entrance and check the height of the truck against the mark on the cig. This is a twist on a basic artist technique for keeping things to scale.

You are given no way to accurately find the midpoint. So with Cheesner's solution, if you are off from the midpoint, your results will be off.

I don't smoke, but I doubt the exact length of a cig is common knowledge. Dej Mar's calculation method wouldn't work if the cig's length was unknown.

your guess is a smart one also.

[Peekay]

From the problem statement, there is no way we can measure the height of the tunnel throughout its entire length! So, all we are trying to measure is the height at the entrance of the tunnel. In that case, isn't is just simpler and more practical to drive as close as possible to the entrance (without getting stuck, of course) and use eye estimation at that point? All this trigonometry stuff with a cigarette held at arms length and no other measuring tools will give a very rough order of estimate anyway.

[wolfgang]

From the problem statement, there is no way we can measure the height of the tunnel throughout its entire length! So, all we are trying to measure is the height at the entrance of the tunnel. In that case, isn't is just simpler and more practical to drive as close as possible to the entrance (without getting stuck, of course) and use eye estimation at that point? All this trigonometry stuff with a cigarette held at arms length and no other measuring tools will give a very rough order of estimate anyway.

The street was (one way),that means,he can not drive close to the entrance and wait to see weather it is possible or not....cause there are another cars on the road.

[Peekay]

The street was (one way),that means,he can not drive close to the entrance and wait to see weather it is possible or not....cause there are another cars on the road.

Well, in that case it is back to the Marlboro I guess! See, I tried my best to stay away from the "cigarette" - as far as possible - not only an arm's length!