A Physics student who got the following question in an exam: "You are given an accurate barometer, how would you use it to determine the height of a skyscraper?"

"Go to the top floor, tie a long piece of string to the barometer, let it down 'till it touches the ground and measure the length of the string".

The examiner wasn't satisfied, so they decided to interview the guy:
"Can you give us another method, one which demonstrates your knowledge of Physics ?"

2: "Sure, go to the top floor, drop the barometer off, and measure how long before it hits the ground......"

"Not, quite what we wanted, care to try again ?"
3: "Make a pendulum of the barometer, measure its period at the bottom, then measure its period at the top......"

"..another try ?...."
4: "Measure the length of the barometer, then mount it vertically on the ground on a sunny day and measure its shadow, measure the shadow of the skyscraper....."

"....and again ?...."
5: "walk up the stairs and use the barometer as a ruler to measure the height of the walls in the stairwells."

"...One more try ?"
6: "Find where the janitor lives, knock on his door and say 'Please, Mr Janitor, if I give you this nice Barometer, will you tell me the height of this building ?"

There are many more ways, for instance:
7: To which the less polite alternative is to threaten to wallop the caretaker with the barometer unless they tell you how high the building is.

The just-released book, "Expert C Programming (Deep C Secrets)", Peter van der Linden, SunSoft/Prentice-Hall, ISBN 0-13-177429-8, lists twenty-one (21) more or less useful ways to measure the height of a building with a barometer.

8: Use the barometer as a paperweight while examining the building plans.

9: Sell the barometer and buy a tape measure.

10: Use a barometer to reflect a laser beam from the top and measure the travel time.

11: Track the shadow of the building positioning a barometer on the ground every hour.

12: Create an explosion on the top and measure the time for the pressure depression indicated on the barometer.