Lecture # 18 SCIENCE 1 ASSOCIATE DEGREE IN EDUCATION FORCE AND MOTION

Overview of the Unit This unit builds a foundation for an appreciation for physics as its own scientific discipline. It provides an understanding of the processes by which physicists increase knowledge in their field. Teachers investigate physics through explorations of force and linear motion.

Week-wise Plan In the first week, they apply forces and cause linear motion at constant speed and direction. Then they move on to accelerated motion in a straight line. In the second week, the study is expanded to motion that can change in magnitude and direction. The third week of this unit develops and deepens the prospective teacher’s pedagogical content knowledge. They can then successfully introduce young children to appropriate concepts related to force and motion.

Teachers focus on the following topics: 1.Motion 2.The laws of motion 3.Concepts of inertia and mass 4.The relationship between action and reaction 5.Force pairs 6.Force and acceleration

Areas of Focus You should make an effort to help Student develop an understanding of the distinction among speed, velocity, and acceleration. The unit identifies a variety of forces considered in Science I (for instance, normal force, friction, gravity, net force).

Learning outcomes for this unit Student Teachers should be able to: 1.articulate and demonstrate the principles of motion and forces and apply them to examples of interactions between objects 2.investigate the relationships among force, mass, and motion of an object or system 3.conduct investigations to determine the position and direction of a moving object (and represent its motion on a graph) 4.draw free-body diagrams that list all the forces acting on an object and the resulting direction of motion

Learning outcomes for this unit continue ……… Student Teachers should be able to: 5.analyse the motion of objects by the classical relationships known as the laws of motion 6.begin to identify the unit’s underlying core science concepts for children in elementary grades 7.design inquiry-based activities and learning outcomes that are age appropriate.

Overall teaching suggestions: Essential core vocabulary Because there are so many misconceptions about forces, it is important that Student develop a clear idea of what force means. Force is an action or agency that acts on a body and can cause a body to accelerate. Generally, they should be able to distinguish between two classes of forces: 1) Contact—types of forces in which the two interacting objects are physically in contact with each other 2) Non-contact—types of forces in which the two interacting objects are not in physical contact but are able to exert a push or pull despite the physical separation.

Overall teaching suggestions: Essential core vocabulary Continue…… Other terms will be important to understand because they relate to the behaviour of all forces on objects. Two key terms are dynamic equilibrium and net forces. Dynamic equilibrium is a condition of flux but with all influences (forces) in balance. It is a term relevant to other areas of science as well, such as chemical reactions. Net force is the sum of the magnitude of all (force) vectors, including the sum of their directions (relative to axes). Vectors are added graphically. As Students attempt to display the magnitude and direction of forces acting on an object, they begin to refer to those representations as free- body diagrams.

A note on misconceptions The most common misconception is the idea that a force can be given to an object. For example, a Student might think that when a force is applied by a hand, the force still acts on the object after the object leaves the hand. As a result, they may identify a force as causing a continuous motion.

A note on misconceptions continue ….. Sometimes, Students might identify this ‘force’ as inertia. Once an object loses this ‘inertia’, it also stops. Thus, they believe that objects move because of some quantity they have been given. In addition, they think it is natural for this quantity to run out and the motion of the object to cease. Another misconception is that a force must act only through contact.

A note on misconceptions continue ….. To deal with misconceptions about the measurement of a moving object, graphs and visual representations are highly recommended. Studies have shown that vector diagrams help Students gain a better understanding about force and motion concepts. A recommendation is for them to use force or free-body diagrams. A force or free-body diagram uses arrows to represent the forces acting on an object at a particular moment. The length of the arrow represents the relative magnitude of the force. The direction of the arrow represents the direction of the force acting on the object. It is also recommended that you consider the time during which forces act and during which speed changes. Failure to do so may be at the root of common misconceptions.