how many gallons of water did a truck fill up if it's weight before the fill up was 3547 lbs and afterwards was 4924 lbs?

depending on the method, 138-139 (imperial) gallons, or 626 L

Explanation:

The wt of water is 4924-3547 lb = 1377 lb = 1377/2.2 kg = 626 kg = 626 L

1gallon = 4.5 L (it does where I come from and who still measures things in imperial anyway?) so I guess  that is 139 gallons

or alternatively, I recall from distant childhood, “a pint of water weighs a pound and a quarter” which means 1 gallon = 10 lb, so 1377 lb = ~138 gallons

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.