Science Buddies: "Ask an Expert"

I have been helping my son with this project. We have followed each step exactly as written. We are now at the part of calculating the viscosity of each liquid. We have all the numbers we need from the charts we did except "g". I don't understand what "g" is or where we get the number. The definition talks about gravity, etc. and says something about 9.81. Do we use that number? We are confused. Any help is greatly appreciated!

Also, the forumlas keep talking about meters and the project told us to measure things in centimeters. So our numbers are based on cm. Do we need to convert to meters?

Thank you for any help!
Confused Mom!
K. Price

g is the acceleration due to gravity. If you drop an item from a height, it starts slow and gets faster and faster as it drops. The rate it gets faster is the acceleration. The best you can ever do is to accelerate in an environment where nothing gets in the way of your accelerating - like in a vacuum. The idea behind this project is that if drop things in something light, like air, they accelerate more rapidly than if you drop them in something heavy, like molasses. You know that some common liquids are thicker and heavier than others - your data will show that the thickest and heaviest make the marble accelerate the slowest and take the longest time to reach the bottom of the tube.

Part of the calculation is knowing how fast an item will accelerate due to the Earth's gravity, and that's 9.81 meters/second^2, and what we call 'g'. Since your measurements are in centimeters (cm) you need to divide them by 100 to convert to meters (m) or convert g from 9.81 m/s^2 to 981 cm/s^2. Your choice.

Thank you so much for the help! We can finish now and I understand about converting too! Blessings to you!!!