Three Scientists on an Island

This past week, we began to solve a problem for some scientists who will be living on a deserted island for a year. They will be studying a very rare bird, but the island has no water or food or any other supplies for them. Therefore, everything the scientists need has to be flown to the island by airplane. The airplane can drop a large crate on the beach, but the scientists' campsite is on top of a 20 meter cliff above the beach. How can they get the crate up to the campsite?

We modeled the cliff with a bent piece of cardboard and the crate with a 1 kg mass. In the story, the scientists find a room full of ropes on a sunken ship down the beach, but the ropes are old and weak. So, we used thread to model the ropes.

Scientists use models to study situations where the materials are too large, too small, too far away, or too dangerous. It is important to remember to consider the actual materials when working with the model.

We decided on the following:

Question:  How many pieces of thread will it take to lift the mass?

Goal:  Lift the mass 20 cm using the thread.

Criteria:

1. The mass must be lifted.

2. The mass must lift 20 centimeters up.

3. We have threads to use.

Constraints:

1. The mass is very heavy.

2. The 'cliff' is straight up.

3. The thread is weak.

When a scientist has a question, she or he tries to think of a way to answer it. The goal in this case was to use the model to simulate the situation on the island. Scientists consider the criteria for reaching their goals; these tell them whether or not their goal has indeed been reached. If their solution addressed each of the criteria, then they have reached their goal.

Constraints are the obstacles a scientist mush overcome to achieve his or her goal. The constraints must be considered in the model because they represent real obstacles in the situation.

The class members tried to lift the weight with one, two, or more pieces of thread. We found that it was difficult to lift the mass without winding the thread around our fingers, without lifting the mass so that our hands lifted in the air—'meters' above the top of the 'cliff!', or without grasping the thread very close to the top of the mass—our scientists would have to have been floating in mid air!.

In short, we need another solution. The rope alone won't be able to help the scientists, although it may be used somehow. We still need to work to improve our model so it can be applied to the actual island.