Name________________
Lab Activity: Mass of a Tree
In this Lab Activity, you will estimate the mass of a tree. To do so, you
will measure the density of wood, the height, circumference and volume
of a tree, and then the mass of a tree. Record all data in your lab
notebook.
Because density is a characteristic property of matter, we can apply the
known density of one substance in order to measure the mass or volume
of another object that consists of the same substance.
Formulae:
Density = Mass / Volume
Mass = Density x Volume
Volume = Mass / Density
Step 1: Measure the density of wood block
Length
Width
Height
Volume
Mass
Density
Step 2: Estimate the height of the tree using the triangulation method.
Very tall objects are difficult or unsafe to measure using a meter stick
or tape measure, so we must estimate using a triangulation method.
Using this method, you will measure the height of a tree along Carr
Road.
1. Hold the 45◦ Angle Block parallel to the ground on the palm of the
hand.
2. Use the side of the block as a site.
3. Holding the 45◦ Angle Block still, move until the top of the object
falls to the top of your site.
4. Measure the distance of from the object to where you are
standing.
5. The total height is that distance plus your height.
Data Table: Height of Tree
Distance of
Triangulation
Tree on
Carr Rd
Your Height
Height of Tree
Step 3: Calculate the Volume of a Tree
The trunk of a tree is shaped like a cone with branches growing out. If
a tree had no branches, it would remain shaped like a cylinder. In other
words, the trunk and branches roughly equate to the volume of a
cylinder. You are able to measure the height of the tree by
triangulation and the circumference at breast height. These two
measurements will let you calculate the volume of the tree by applying
them to the volume of a cylinder.
Formulae: Make sure you make proper metric conversions.
Diameter of Tree:
diameter = circumference at breast height / 
d = cbh / 
Radius of Tree:
radius = diameter / 2
r=d/2
Volume of Tree (assume tree to be a cylinder)
Volume = height x radius squared x 
Meters Cubed to Liters:
Circumference
(m)
Diameter
(m)
v = h r2 
m3 = 1000 L
Liters = Meters Cubed x 1000
Radius
(m)
Height
(m)
Volume
(m3)
Volume
(L)
Step 4: Mass of tree
Once you have measured the volume of the tree and the density of the
wood, you can calculate the mass of the tree. Make sure you convert
density of the wood to kg / L
Mass = volume x density
m=dv
Grams / Cubic Centimeter To Kilograms / Liter
g/cm3 = kg / L
Density of Wood (kg / L)
Volume of Tree (L)
Mass of Tree