Question

 

Activity 1

Record your data from Activity 1 in the boxes below. Enter the data for the sample you used in each trial (5000 rpm, 10000 rpm, etc…) in the appropriate columns and the corresponding g-force, number of layers, and position of layers position results.

You will need to use the following formula to assist with your laboratory report:

G-force =0 00001118 x radius of centrifuge arm x (rpm)²

The radius of the centrifuge arm for this instrument is 10 cm.

Speed	5000 rpm	10000 rpm	15000 rpm	20000 rpm
G-force	2795	11180	25155	44720
Number of Layers	2 layers	4 layers	5 layers	3 layers
Position of Layers	1 in the top and 1 in the middle	2 in the top and 2 in the middle	2 in the top, 2 in the middle and 1 filling bottom in the tube	2 in the top, and 1 filling bottom in the tube

QUESTIONS!

1. Explain what happens to the G-force as the speed of the centrifuge increases.

2. Which is likely the best speed to separate the components of this soil sample? Why?

3. Describe in which layers you are likely to find the organic matter, gravel, sand, silt, and clay at the following speeds:

5000 rpm

15000 rpm

 

Answer 1

1). as the speed of centrifuge increases.

we can see from the formula above that: G-force =0 00001118 x radius of centrifuge arm x (rpm)2

  G-force   speed of centrifuge

G-force (rpm)²

so G-force increases square proportional to speed of centrifuge

example: as speed increases from 5000 rpm to 20000 rpm( 4 times ) then G-force increases almost 16 times.

2).15000 rpm that has the most amount of separated components on its flask. It’sfast enough to separate them. see that there are total 5 layers are there.( 2 top, 2 middle, 1 bottom). so more elements are separated.

3).AT THE  speed 5000 rpm we find .

sand and gravel most likely at the bottom from being the lightest while silt and clay are most likely at the top for being a little heavier also the speed is not high enough to separate them all.

At the speed 15000 rpm they are spread separately with each layer holding one element also considering the speed its high just enough to separate each one of them.