Snow on a roof and water in gallons when it melts

Question

you received 7.87 inches of snow in a storm. your roof is covered in snow. the area of the roof is 400 sq ft. that is 122 square meters or 122000 square cm. Calculate the weight of the snow in pounds on your roof and how much water in gallons you can get when the snow melts.

Answer 1

These questions are entirely driven by the fact that the US uses non metric measurements (like gallons or pounds) which have to be converted to their metric equivalents (like cm^3 and grams). In this case, the key piece of information here is that the density of water is 1 g/cm^3 by definition where g is a measurement of weight and cm^3 is a measurement of volume.

 

To get the volume, you have to multiple the area of the roof by the height of snow. Before you can start multiplying, you have to convert the height of snow to something available for the area of the roof. We want cm^3 so convert 7.87 inches to cm and multiply that amount by 122000. Let's call that X cm^3.

 

According to the density of water, X cm^3 equates to X grams of snow. Convert that to pounds and you have the weight of snow.

 

The gallons of snow is a lot easier because gallons is a measurement of volume, usually compared to liters. This is where it is handy to know that 1000 cm^3 is one liter. So convert X cm^3 to liters and then to gallons and you're all set!