Physical Science

Newton's Apple Meets the Seat Belt

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Content Objectives:
Students will be able to:

1.   Identify the concepts of Newton’s three Laws of Motion.

2.   Explain the purpose of a seat belt in relation to at least one of Newton’s laws.

Process Objective: 

Students will be able to:

Demonstrate at least one of the Laws of Motion in relation to the principle and purpose of the seat belt or other safety device of a vehicle.

1.   Teacher observation

2.   Evaluation of demonstration (see scoring rubric)

Procedures:

1.   After a brief introduction of the story of Sir Isaac Newton’s discovery of gravity because of an apple, the three laws should be introduced with brief demonstrations. (See sample demonstration for ideas.)

2.   After demonstrations and further discussions of the laws, challenge the students to apply the Laws of Motion to the use of safety devices installed in vehicles. The following can be used as an introduction to the task:

          The Auto Manufacturers of America have asked you to “prove” Newton’s Laws of Motion in relation to the seat belt and child restraint seats. Incredibly, some people still don’t wear their seat belts or restrain their children in a child safety seat because they believe that they will be able to stop themselves and/or their child from going forward in an accident.

          Your task is to create, with your partner(s), a demonstration that shows what happens with and without a seat belt in an accident and to identify and explain the law related to your demonstration.

Extension Assignment:

Create a demonstration that illustrates at least one of Newton’s Laws of Motion and the advantages and/or disadvantages of other safety devices installed in cars.

Option: To tie in the story of the falling apple, provide each child with an apple to represent the person in the vehicle.

Standard Category:
3.4 Physical Science, Chemistry and Physics

Materials:
Carts, cars or other wheeled vehicles that can hold an apple(s) or other material as chosen by the teacher

Various sizes of balls

Marbles

Ramps

Paper

Instructional Strategies:
Experimentation

Cooperative learning

Demonstration

Related Concepts:

Public speaking

Sample Demonstration

First Law of Motion: An object at rest will remain at rest unless acted upon by another force. An object in motion will remain in motion unless acted upon by another force.

Demonstration: (Simple) A ball sitting on the table is at rest until hit by your hand (a force) that sends it into motion. A ball thrown through the air is acted upon by the wall it hits and gravitational pull (two forces).

(More Complex) A ball sitting on a cart will remain at rest, but when the cart is being pushed, the ball is also being moved (just as a person sitting in a car is moving). When the cart suddenly stops, the unrestrained ball will continue forward until stopped by another force. The teacher will have to decide whether or not to use this demonstration since it might influence on the demonstrations that the students choose to illustrate a Law of Motion.

Second Law of Motion: A net force acting on the object causes the object to accelerate in the direction of the force. Acceleration is affected by the size of the force and the mass of the object. Another way to express this law is F = M x A, read as “force equals mass (kg) times acceleration” (m/s ²).

Demonstration: Acceleration is a difficult concept at this age level, but mass can easily be compared and therefore some conclusions can be ascertained about force. Compare a large ball (e.g., softball, field hockey ball and baseball) with a marble. Ask the students which one will have more force to tear a sheet of paper and why. If anyone asks how fast the items are traveling, explain that they will be traveling at approximately the same velocity (although an extension can be conducted, varying the velocity or direction, thereby introducing the concept of acceleration).

Have two students hold a piece of paper (paper towels or toilet paper could also be used) taut or set up a contraption to hold it taut at the bottom of the ramp. Adjust the height of the ramp and release the ball and marble from the top until the ball is able to rip through the paper. What made it possible for the larger ball to rip through the paper, although the marble did not? The mass of both objects should be measured after the students uncover the answer.

Extension: Can the marble ever rip through the paper? Experiment with this possibility and begin the concept of acceleration.

The Law of Motion: When one object exerts a force on a second object, the second object exerts a force on the first that is equal in size, but opposite in direction. Another way of saying this is: “For every action there is an equal, but opposite, reaction.” It is important to remember that not all forces are balanced, although they are equal in size.

Demonstration: (Balanced Forces) Have students sit back-to-back on the floor and interlock their arms. Encourage them to stand straight up by using the other person as their balancing force. They should push their backs against each other, but the greatest challenge is to maintain a balanced force (although their masses may be quite different).

(Unbalanced Forces): Using a track, or other small area, send two balls or a toy truck and toy car at each other as in a head-on collision. Allow students to observe the reaction of each object. 

Extension: Allow students the opportunity to experiment and measure the reaction of each object in various head-on collisions.

Scoring Rubric

Standard Category: 3.4 Physical Science, Chemistry and Physics 

Suggested Grade Level: 5-7

Standard Objective:

Demonstrate at least one of the laws of the Laws of Motion in relation to the principle and purpose of the seat belt or other safety device of a vehicle.

Title of the Task: A Vehicle’s Safety Features and the Laws of Motion

Advanced:
Working in a cooperative group, students relate at least two of the Laws of Motion in one demonstration. In addition, students verbally explain the Laws of Motion that are being demonstrated, in addition to the last law and the relationship of this law to the safety features in vehicles.

Proficient:
Working in a cooperative group, students create a demonstration that shows the necessity of seat belts or some other safety feature. In addition, students verbally explain the Law of Motion that is being demonstrated and at least one other Law of Motion and how it is related to safety features in vehicles.

Basic:
Working in a cooperative group, students create a demonstration that is similar to the teacher’s demonstration. In addition, students verbally explain the Law of Motion that is being demonstrated.