2.3 Protect Yourself

Following our explorations of Newton's Second Law and the Law of Conservation of Momentum, we are tasked with putting them together to save lives.

Using this equation as a guide, how will you ensure that your 'cargo' remains intact during a collision?

Disciplinary Core Ideas

PS2.A: Forces and Motion

If a system interacts with objects outside itself, the total momentum of the system can change; however, any such change is balanced by changes in the momentum of objects outside the system. If you expand your system, the momentum is still conserved.

ETS1.A: Defining and Delimiting an Engineering Problem

Criteria and constraints also include satisfying any requirements set by society, such as taking issues of risk mitigation into account, and they should be quantified to the extent possible and stated in such a way that one can tell if a given design meets them. (secondary)

ETS1.C: Optimizing the Design Solution

Criteria may need to be broken down into simpler ones that can be approached systematically, and decisions about the priority of certain criteria over others (trade-offs) may be needed. (secondary)

Apply science and engineering ideas to design, evaluate, and refine a device that minimizes the force on a macroscopic object during a collision.

Crosscutting Concepts

Cause and Effect

Systems can be designed to cause a desired effect.

Science and Engineering Practices

Constructing Explanations and Designing Solutions

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.

Apply scientific ideas to solve a design problem, taking into account possible unanticipated effects.

TASK: Compete in one of the following:

Protect your Head Helmet Design
Impact is inevitable.

Impulse - Collins

The Common Link

Impulse-momentum Theory - An understanding of how the impulse-momentum theorem was used as a guide in the creation and refinement of your protective device. A sketch of your system with reference to specific portions of your device and how they relate to the equation should accompany your presentation.

Rubric will be based upon the following criteria

Using scientific knowledge to generate the design solution
1. Students design a device that minimizes the force on a macroscopic object during a collision. In the design, students:
  1. Incorporate the concept that for a given change in momentum, force in the direction of the change in momentum is decreased by increasing the time interval of the collision (FΔt = mΔv) or reducing the change in velocity of the object prior to the collision.
  2. Explicitly make use of the principle above so that the device has the desired effect of reducing the net force applied to the object by extending the time the force is applied to the object during the collision.
  3. Explicitly make use of the principle above so that the device has the desired effect of reducing the net force applied to the object by reducing the change in velocity of the object prior to the collision.
2. In the design plan, students describe the scientific rationale for their choice of materials and for the structure of the device.

2. Evaluating potential solutions

1. Students describe and quantify (when appropriate) the criteria and constraints, along with the tradeoffs implicit in these design solutions. Examples of constraints to be considered are cost, mass, the maximum force applied to the object, and requirements set by society for widely used collision-mitigation devices (e.g., seatbelts, football helmets).
2. Students systematically evaluate the proposed device design or design solution, including describing the rationales for the design and comparing the design to the list of criteria and constraints.
3. Students test and evaluate the device based on its ability to minimize the force on the test object during a collision. Students identify any unanticipated effects or design performance issues that the device exhibits.

3. Refining and/or optimizing the design solution

Students use the test results to improve the device performance by extending the impact time, reducing the device mass, and/or considering cost-benefit analysis.

Rationale for limited supplies:

This is a logarithmic scale, each increment on the y-axis is 10x greater the the previous. For example, Falcon 1 (2006) is approximately 1/10 the cost of the Space Shuttle (1981), and Falcon Heavy (2020) is 1/10 the cost of Falcon 1.

Engineering Challenge Organizer

Please make a copy of this for your own guidance

Protect Yourself Summative Video

Summative Rubric (Subject to minor adjustments)

Protect your Head

Impact is Inevitable

Helmet Design

Using a model head, design a self contained helmet that will protect your model head using minimal materials. Collect data to quantify the effectiveness of your device.

Competition Guidelines:

Model Head:
- Must be made of material that will allow for quantification of damage.
  - Low quantification:
    - 1 = Survived, 0 = Broke
    - Egg, water balloon.
  - Medium quantification:
    - Deformation, difficult to reset between trials
    - Styrofoam
  - High quantification:
    - Amount of deformation, able to be remolded to original shape between trials
    - Play-dough (homemade), Plasticine, similar material
    - Elastic Ball: video capture of deformation
Protective Helmet:
- Lowest Mass of Device to Mass of Model Head Ratio
Competition Parameters:
- Drops will begin at 1 meter and raise 0.5m, until a winner has been determined. Lowest point of helmet/head system at drop height.

Car Crash Protection

Using a model car and your phone's accelerometer (all phones have them), minimize the forces acting on your car during a head on collision.

Competition Guidelines:

Car Crumple Zone - Car/Phone System:
- Must be made of material that will allow for repeatable trials.
- Determine acceleration curve of car crashing without protective device.
- Repeat at increasing velocities (determined by accelerometer) to determine limit of protective device.
  - Some apps to use:
    - PhyPhox
    - Arduino Science Journal
      - Android
      - iOS
- Lowest mass of Crumple zone device to car/phone mass ratio awarded the highest points.
Car/Phone System:
- Phone safety outweighs all other aspects of this activity.
Based on the data collected by your accelerometer, a winner will be determined.

7 Minutes of Terror

Mars Lander -

Using a mass similar in size to an egg (egg, play-dough, plasticine, etc) and 5 sheets of paper, create a self-contained device that will protect your Mars Lander.

Mars Lander (Protected object)
- Must be made of material that will allow for quantification of damage.
  - Low quantification: Egg, water balloon. (1 = Survived, 0 = Broke)
  - Medium quantification: Styrofoam (Deformation, difficult to reset between trials)
  - High quantification:
    - Play-dough, Plasticine, similar material (Amount of deformation, able to be remolded to original shape between trials)
    - Elastic Ball: video capture of deformation
Protective Device (You are limited to the following materials)
- 4 sheets of A4 paper
- 1 meter of 0.02 m wide tape (0.02 sq meters)
Competition Parameters:
- Drops will begin at 2.5 m and raise 0.5 m until a winner is determined.

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