Materials Included In Kit

Additional Materials Required

Prelab Preparation

1. Set up rig the same day you introduce the project so students understand the setup.
2. To set up the rig
   1. Attach 2 ceiling hooks to the metal frame of a suspended ceiling. If possible, remove a ceiling tile and find a metal frame that is secured to the building’s framework.
   2. The nylon string is weighted to hold 10 pounds. Extra nylon string is included in the kit.
   3. The ceiling hooks are weighted to hold 5–10 pounds. Extra ceiling hooks are included in the kit.
   4. Securely attach one piece of nylon string to each ceiling hook.
   5. Cut the nylon string so that it is about waist level (3–4 feet above the ground).
   6. Attach a carabiner to each string. The carabiner serves as an easy attachment site for the student’s vehicle suspension.
3. After introducing the project, either take the rig down or tie it up so students do not play with it.
4. Day of competition
   1. Lower the rig.
   2. Move desks to the perimeter of the room.
   3. Set up plenty of newspaper under the rig area.
   4. Assign judging roles (see Lab Hints).
   5. Post the Single Elimination Bracket (Teacher PDF).

Safety Precautions

Due to collisions, student must wear safety goggles. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory.

Lab Hints

• Enough materials are provided in this kit for two rigs to be set up or to be kept as replacement parts. The introduction and prelab portion of this activity can reasonably be completed in one 50-minute class period. The competition will take approximately two 50-minute class periods.
• Assigning roles for students to judge each other’s vehicles helps move the competition along and keeps students actively engaged during the competition. Roles may include:

  Materials Judge—Determines whether the materials in the vehicle will create harmful fragments. 
  Weapons Judge—Determines whether any "weapons" are sharper than a blunt pencil end. 
  Mass Judge—Uses the spring scale to ensure the vehicle is under 10 N (1 kg). 
  Dimensions Judge—Uses a ruler to ensure the vehicle is within 30 cm x 30 cm x 30 cm. 
  Suspension Judge—Uses a ruler to ensure suspension is 10 cm from the top of the vehicle and checks that there is a loop to attach to the carabiner. 
  Egg Visibility Judge—Ensures that the top half of the egg is visible and no sticky material is holding the egg in place. 
  Contest Judge—Determines winner of individual battles; looks for cracks in eggs (without touching). 
  Bracket Manager—Fills in the bracket during the competition
  Rig Assistant (2)—Assists competitors in hooking up their vehicles to prevent damage to egg prior to battle. 
  Clean-Up Crew (2)—Cleans up soiled newspaper after battle and replaces with fresh newspaper

• Students will only get one egg. If the egg breaks prior to battle, the contestant is eliminated (teacher discretion).
• Materials included in the kit are for the competition. Students will need to make their own vehicles using supplies from home.

Teacher Tips

• This activity is an excellent opportunity to include a STEM project as a culmination activity for Forces and Motion unit.
• Connect this activity to the real world by discussing inertia and car accidents, especially the importance of seat belts, crash test dummy simulations and other safety measures.
• Students build their vehicles independently over several days. Slight modifications prior to competition are to be expected. It may be helpful to designate a modification work area with extra scissors, rulers and other materials.
• Creating a checklist for the judges to initial is useful.
• Edit the Egg Elimination Bracket to fit your class size. You can include randomly placed, first-round byes if your class size is under 32 or an odd number.
• Hang the spring scale from the ceiling so the vehicle can be attached and untouched while mass measurement is being taken by the Mass Judge.
• Warn students that using weak materials to attach the suspension system (i.e., transparent tape) to the vehicle will not be sturdy enough during battle and will typically result in elimination.

Answers to Prelab Questions

1. Describe how an unbalanced force causes an object to accelerate.

   Unbalanced forces cause an object’s motion to accelerate either because the forces are acting in opposite directions and are unequal in size or the forces combine, working together in the same direction, causing acceleration.

2. Explain which of Newton’s laws of motion is being applied in Figure 4.

   Newton’s third law of motion is demonstrated in this figure. The action force is the person pushing on the ground to make the skateboard move forward. The reaction force is the ground pushing on the person’s foot with equal but opposite force.

3. Describe the type of design you think will be most successful during the Egg Elimination competition? Remember to apply physics concepts to your design.

   Student answers will vary. For example, students may focus on building a large vehicle with maximum capacity for mass to increase destruction during the collision due to momentum. Building a vehicle that maximizes safety while applying Newton’s first law of motion (inertia) to secure the egg during impact tends to be successful in competition.

Answers to Questions

1. Describe the strategy implemented for the design of your vehicle. Include how the concepts of force, momentum and Newton’s laws of motion were incorporated into your design.

   Student answers will vary. Design specifications related to physics concepts must be included in answer.

2. Describe what happened during the competition. Explain how far you got within the bracket elimination competition and why you won or lost each battle.

   Answers should not include remarks about other vehicles being unfair, but rather focus on physics concepts the other vehicle employed or that their vehicle lacked.

3. Explain, in detail, what changes you would make to your design to improve its effectiveness during competition.

   Most likely answers will include developing a restraining device to hold their egg in place to prevent the egg from continuing to travel forward after the collision. Also, students will most likely mention weak suspension systems (lacking secure attachment).

4. Discuss the importance of factoring in inertia during the design process of your vehicle.

   Inertia is an object’s tendency to resist a change in motion. Therefore, if a vehicle’s motion suddenly stops, as in a collision, other objects, like passengers or the egg, will have the same velocity as the vehicle and continue moving at the vehicle’s speed unless restrained. The concept of inertia needs to be taken into account and the design needs to promote a slow deceleration or restrain the passenger or egg to avoid serious injury.

5. Explain how vehicle air bags are effective in reducing injury during collisions.

   Stopping an object’s momentum requires force acting over a period of time. During a collision, that time is very short. When a collision occurs, the vehicle’s momentum stops instantly while the passenger’s does not, so the goal of the air bag is to slow the passenger’s forward motion evenly with little or no damage.

Teacher Handouts

14064_Teacher1.pdf

Introduction

Why do athletes wear protective equipment? For example, how do shoulder pads protect a football player? Shoulder pads are made from a hard, plastic outer covering with foam padding underneath. Two protective measures come from wearing shoulder pads; the pads absorb some of the shock from impact and then distribute the shock through a larger pad designed to regulate the players’ body temperature during competition and protect against injury.

Concepts

• Force
• Momentum
• Inertia
• Newton’s laws of motion

Background

Motion of an object is any change in its position. The change is caused by a force—any push or pull that one object exerts on another. Forces are either balanced or unbalanced. If the forces are balanced, then they act on an object in opposite directions, but are equal in magnitude and therefore, the object’s motion does not change. Unbalanced forces result when the net force on the object is not zero and the object’s motion accelerates. Two situations can create unbalanced forces. First, the two forces act on the object in opposite directions, but the magnitude of each force is not the same, so the net force will occur in the direction of the larger force. The second situation occurs when the two forces are acting in the same direction; therefore the forces combine (see Figure 1).

Newton’s laws of motion cover two main concepts: inertia and acceleration. Newton’s first law of motion is also known as the law of inertia. Inertia is the tendency of an object to resist change in its motion. Newton’s first law states that an object moving at a constant velocity will continue moving at that velocity unless a net force acts upon it (see Figure 2). The same is true for an object at rest; it will stay at rest unless a net force acts upon it. An excellent example of Newton’s first law is during a car crash. If a car that is traveling 50 km/h collides with a solid object, the car crumples, slows down and stops within 0.1 second. Passengers in the car will continue traveling forward at the same speed due to their inertia, unless wearing a seatbelt. Newton’s second law of motion relates to the acceleration of an object. The acceleration is equal to the net force acting on the object divided by the object's mass. The acceleration of the object is in the same direction as the net force. Deceleration occurs when the net force acts in the direction opposite the object’s motion. Referring back to the car collision and seatbelts, the seatbelt opposes the passenger’s forward motion and decelerates the passenger to prevent serious injury.

Newton’s third law of motion states that forces exist in pairs. Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object. This is often referred to as “action reaction forces.” A common phrase to summarize Newton’s third law is “for every action force there is an opposite and equal reaction force.” An easy example is if you push your hand against the wall (action force), the wall pushes back against your hand with equal and opposite force (reaction force). The forces do not cancel each other out because they are acting on separate objects (either your hand or the wall).

The final concept that needs to be addressed is momentum. Momentum is the product of an object’s mass and velocity. Momentum can be large if the object’s mass is large, like that of an elephant or if its velocity is large, like that of a cheetah. When an object is at rest, since its velocity is zero, its momentum is zero. Conservation of momentum occurs in a closed system, meaning other objects and forces do not enter or leave the system. When two objects collide within a closed system, momentum is conserved, meaning there is no increase or decrease in momentum. The loss of momentum of one object will equal the gain in momentum of the second object, thus conserving momentum (see Figure 3). Safety during a collision requires the knowledge of physics and proper implementation. According to the National Highway Traffic and Safety Administration, the use of seat belts during car crashes saves the lives of approximately 13,000 people each year. Seat belts have been designed to combat inertia and momentum. Seat belts are designed to apply a stopping force to durable parts of the body, like the rib cage and pelvis, over a longer period of time to reduce injury. Air bags have also become extremely popular and protective, reducing the risk of death in a head-on collision by 30 percent. The air bag behaves similar to the seat belt by extending the time to stop the passenger’s momentum during the collision. Air bags work within two specific constraints, the space between the passenger and the steering wheel or dashboard and a fraction of a second. Working together, seat belts and air bags help stop the passenger while doing as little damage to him or her as possible.

Experiment Overview

In this activity, the concepts of force, momentum and Newton’s laws of motion will be applied to design and build a vehicle that will carry and protect a raw egg during a head-on collision with another egg-carrying vehicle.

Materials

Prelab Questions

1. Describe how an unbalanced force causes an object to accelerate.
2. Explain which of Newton’s laws is being applied in Figure 4 to the right?
   {14064_PreLab_Figure_4}
3. Describe the type of design you think will be most successful during the Egg Elimination competition? Remember to apply physics concepts to your design.

Safety Precautions

Wear goggles during the entire activity and remain in your assigned seat during each collision. Please follow all laboratory safety guidelines.

Procedure

Design a vehicle using materials of your choice that will carry and protect a raw egg during a head-on collision with another vehicle. Be sure to follow all design criteria and constraints below, otherwise you will be disqualified and unable to compete. Make a scale drawing of your vehicle on the Egg Elimination Worksheet.

Part A. Vehicle Materials and Specifications

1. No materials may be used that break and create harmful fragments (e.g., glass, ceramic).
2. The total mass of the vehicle cannot exceed 10 N or 1 kg (2.2 pounds).
3. The dimensions of the vehicle cannot exceed 30 cm x 30 cm x 30 cm.
4. One half of the egg (grade A, large) must be visible and left unprotected from all sides.
5. The egg must be the highest point on the vehicle, except for the suspension system.
6. The egg cannot be held in place by any adhesive (e.g., glue, sticky tack).
7. Vehicles must have a suspension system with loops that will hook up to the rig. The suspension system must measure exactly 10 cm from the top of the vehicle (including the loops) (see Figure 5).
   {14064_Procedure_Figure_5}
8. Offensive weapons may be used, however, they cannot be sharper than an unsharpened pencil (must have a blunt end).

If any of the following specifications are not met, you will be disqualified from competition.

Part B. Contest Rules

1. Single elimination pairings will be randomly selected.
2. Vehicles will be crashed together until one egg cracks, breaks, falls out of the vehicle or if the vehicle falls off its suspension.
3. If any of the above happens to both competitors, both are eliminated.
4. No repairs or adjustments can be made during a battle. Adjustments can only be made after a winning collision.

Student Worksheet PDF

14064_Student1.pdf