Using Models to

Estimate the Mass of Dinosaurs

Advanced preparation

It will take at least one hour to modify ten - one gallon plastic paint buckets. Cut a 5/8 " hole in the front of the bucket about 5/8 " from the top. Insert a piece of rigid plastic tubing (5/8" in diameter and 2" long) into the bucket.

It will take another twenty minutes to assemble the rest of the materials. If the students want to work with more than two models, the lab with take two days

Introduction

Models are important in our lives. You may not realize it, but you deal with models every day. Role models help us understand how we should act. Fashion models help us understand how clothes will look when they're worn. Behavior models help us understand why people behave the way they do. In science, models help us understand complex scientific theories and concepts. Watson and Crick used paper cutouts and ball and stick models to explain DNA structure. Bohr used a model of our solar system to explain the movement of electrons in the atom. Einstein used a model of a person in a sealed elevator traveling though space to explain the implications of relativity.

Models come in many different forms. Some don't resemble the objects they represent; instead they act like the objects they represent. (Electrons in an atom don't really look like planets in our solar system,) Other models, like cars, airplanes or dinosaurs, look like the objects they represent, but they are built on a smaller scale and are made of less expensive materials.

Objectives

The students will:

* Determine the volume of a dinosaur scale model using Archimedes Principle.

* Calculate the volume of an actual dinosaur from the volume of the scale model * Apply the concept of density to the volume of the actual dinosaur to calculate the mass of the dinosaur.

* Explain the use of models to further scientific understanding.

Materials

(per lab group)

1. 2 dinosaur scale models

2. One gallon plastic bucket with tube attached (if you use the large dinosaur models you will need larger paint buckets, or rectangular plastic garbage cans)

3. 100 or 250 ml graduated cylinder

4. 250 ml beaker

Fig. 1. Bucket, beaker set-up.

Procedure

1. Place the 250 ml beaker under the plastic tube which will act as a spout.

2. Pour water into the bucket until the water begins to pour out of the spout.

3. Wait until the water stops dripping out of the spout.

4. Remove the beaker, pour the water into a waste container, dry the beaker, and replace it

under the overflow tube. See Fig. 1.

5. Pick your favorite dinosaur from the sample box. Be sure it will completely fit into the

one gallon bucket.

6. With the beaker under the overflow tube, place the dinosaur into the bucket until it is

completely submerged.

7. Wait until the water stops dripping out of the spout.

8. While you are waiting, record the name of the dinosaur in the table below. Also record

its scale.

9. Remove the beaker and pour the water into the graduated cylinder.

10. Record the volume of water displaced by the dinosaur in the table.

11. Repeat with another dinosaur model.

Data

 Trial    Name of Dinosaur      Scale     Volume of Water    Actual Volume  of   
                                           Displaced (ml)    Real Dinosaur (ml)  
   1                                                                             
   2                                                                             

Analysis

1. Determine the scale of the model (The model will have the length of the actual dinosaur.i.e., 6 meters. Measure the length of the model, if is 15 cm long , then the scale is 6 / .15 or 40 /1 (40:1).

Calculate the volume volume of an actual dinosaur. To do this, look at the scale on your model. Since you are working with volumes, which are in cubic dimensions, you have to multiply the volume determined in this experiment by the scale of the dinosaur cubed. Thus, if the scale if 40 you will have to multiply your volume by 40 X 40 X 40 = 64,000.

Show your work below, and record your answer in the data table.

(Most dinosaur models are 40 to 1)

For example, a small dinosaur has a volume of 200 ml, therefore the volume of the

actual dinosaur is 200 ml x 64,000 = 12,8000,000 ml = 1.28 x 10 7 ml

2. Since most of a dinosaur was made up of skin, guts, blood and stuff, we will assume

the density of a dinosaur was 1.0 g/ml. This is probably a good approximation,because

this is also the approximate density of water, crocodiles and mammals. Find the mass

of an actual dinosaur, using 1.0 g/ml as its density and the volume from the data table. Show your work below. (Remember that density = mass/volume.)

1.28 x 107 ml x 1.0 g /ml = 1.28 x 107 grams

3. Convert the answer from Question 2 to kilograms.

1.28 x 107 g x 1x 10-3 kg/g = 1.28 x 104 kg

4. Convert the answer from Question 3 to metric tons. (There are 1000 kilograms

in a metric ton.)

1.28 x 10 4 kg x 1 x 10 -3 metric tons/kg = 12.8 metric tons

5. Convert the answer you found in Question 4 to pounds. (There are 2,205 pounds in a

metric ton.)

12.8 metric tons x 2,205 pounds / metric ton = 28,224 pounds

6. If a full grown African male elephant weighs about 5 metric tons, how many elephants

would it take to equal the mass of your dinosaur.

12.8 metric tons x 1 male elephant = 2.56 or approximately 3 male elephants

5 Metric tons

7. Using your body weight, determine how many times heavier than you a dinosaur is.

Dinosaur weight 28,224 lbs The dinosaur is 1,568 times heavier

Your weight 180 lbs

Conclusion

1. List some advantages to using scale models in this experiment, as opposed to the actual

dinosaur.

Answers will vary, students might include:

Safety, cost, simplicity of procedure, no intervention of the SPCA,

no violation of the endangered species act, etc.

2. Assume dinosaurs were still alive, list some disadvantages to using a model as opposed

to an actual dinosaur in order to determine its mass.

Answers depend on accurate lab procedure and correct mathematical computation. Each step in the procedure introduces a source of error.

The use or misuse of significant figures will alter the results.

3. What assumptions were made in this lab which were not verified?

We assumed that the density of a dinosaur was similar to that of mammals and

crocodiles. Our assumption may be erroneous. If dinosaurs existed, we could

find the mass of the dinosaur directly to determine its density

We assumed that all dinosaurs are alike, if they actually existed we would be able to determine the mass and density differences in the various species of dinosaurs

4. What information was necessary before the model we used could be built? How was

this information gathered?

The various species of dinosaur, their skeletons and approximate body sizes

The densities of other similar animals

The information was gathered over a long period sof time by various investigators

interested in past and present animal life.

5. What are some similarities and differences between scientific models and non-scientific

models?

Both are used to explain complicated ideas or processes

Both are used to link the past to the present and to the future.

Neither is completely accurate or foolproof

Both are subject to revision as we learn more about science and non-science issues.