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In this activity, students will design and build a support structure that will hold their science textbook. After this has been successfully accomplished, students will hold a contest to determine whose structure can hold the greatest number of science textbooks without collapsing.
An object is considered at equilibrium when the net force acting on it is zero. In other words the force of gravity (downward force) is balanced by a "normal force" (upward force) caused by a structure that supports the object. When an object is in equilibrium, there is no change in motion, so it is at rest (as in this case) or moves at constant velocity.
According to Newton's second law, a net force causes an object to accelerate. In this case, the sum of the normal force and the weight is zero represents the net force acting on the object. There is no acceleration and the object remains in equilibrium.
When the object falls, breaking the structure, the normal force exerted by the structure was insufficient to offset the weight of the object. The net force is no longer zero. The weight of the object is greater than the normal force. Now the object accelerates downward (in the direction of the greater weight) until it strikes a surface whose normal force will balance the object's weight.
To design a structure capable of holding a textbook using the materials supplied.
To demonstrate that the weight of a textbook is offset by the normal force exerted on the book by the structure.
To estimate the normal force exerted by the structure on the textbook the instant before structural failure.
Each pair of students will receive the following items for this competition:
20 pieces of dry fettuccini
one meter of masking tape
piece of paper
medium weight book
The height of each students structure shall be at least 5 cm, supporting the book 5 cm above the table. All parts of the book should be supported at least 5 cm above the table.
The structure shall use all or part of the 20 pieces of fettuccini and all or part of the 1 meter of masking tape. No additional tape or pasta may be used.
Tape must be used to secure the support structure. The structure must be one unit that can be picked up and placed on the testing area. Overlapping, non taped pieces of fettuccini are not allowed. Any or all versions of a "column" of fettuccini pieces circled by tape are not allowed. A :log cabin" type structure consisting of overlapping, taped pieces of fettuccini are not allowed.
The final structure must have a minimum of three points of support.
Design and build a support structure according to the design requirements.
Measure and record the mass of the structure. Measure and record the masses of the paper, the lightweight book, the medium weight book and the science textbook.
Measure and record the dimensions of the structure. Note minimum height requirements!
The students will test the integrity of the pasta structure by placing the piece of paper on the structure first. The paper is removed, and the lightweight book is placed on the structure. The lightweight book is removed and the medium weight book is placed on the structure. Last the medium weight book is removed and the science textbook is placed on the structure. To be successful, the structure must hold the item for ten (10) seconds.
Continue loading structure with science textbooks until structural failure occurs.
Calculate the weight of the object (or objects) held just prior to structural failure. Calculate the normal force exerted by the structure just prior to structural failure.
Calculate the efficiency of your structure by comparing the maximum mass held by the structure to the structures mass.
What happens to the structure when the normal force is less than the objects weight?
Which part of the structure collapsed or broke first? Why do you feel the structure broke or collapsed ast this point? What would you do to make your structure stronger at this point?
|Piece of paper
|Medium weight book
|Little or no effort on
questions. More work required
0 - 11
|Questions attempted, many
errors or incomplete thoughts
12 - 15
|Questions answered with
very few errors
16 - 17
|Questions answered with no
18 - 20
|No attempt made or very minimal effort shown||Attempted Homework with some success||Attempted Homework with much success||Completed Homework and demonstrated knowledge gained by including pictures and written description|