Chapter 3: Methodology
3.3 Materials
3.3.2 Newton’s Second Law of Motion Lab Simulation
NSLOM is a fundamental and useful equation in mechanics. The law addresses the relationship between force and motion (Mico, Mandili, Tahiri & Muco, 2010).
NGSS (2013) describes the NSLOM as the following “The movement of an object depends on the sum of the forces acting on it”. If the total force affecting an object is not zero, then its movement will change. The greater the mass of an object, the more force is needed to achieve the same change of motion. For any given object, greater forces cause greater movement changes" (NGSS, 2013, p. 59).
Consequently, by analyzing the NSLOM, it can be summarized as the acceleration of the object is directly proportional to the force and inversely proportional to the mass of the object. The equation of this law is F = ma [ Net force
= (mass)(acceleration)] (NGSS, 2013; Serwey & Jewett, 2014; Itza-Ortiz, Rebello &
Zollman, 2004).
According to Mico, Mandili, Tahiri and Muco (2010), Newton’s second law of motion in many textbooks often presented so abstractly that students cannot see the relationship between force and motion. It is vital to allow students to know the relationship between force and motion (Mico, Mandili, Tahiri & Muco, 2010). Figure 4 represents the types of forces and how they relate it to motion. To enhance the theoretical understanding of how objects move and how they accelerate, interactive simulations of the forces and computational motions obtained from PhET are used as inquiry tools for students (Adams et al., 2008), because PhET simulations provide a high degree of interaction between user control, dynamic feedback, and multiple representations (Adams et al., 2008).
Figure 4: Concept Map that Analyze the Types of Forces
The NSLOM simulations that was used in the current study was a java-based program that is downloaded and installed on student’s computers from the site http://phet.colorado.edu. Which is free to use (see Appendix H). Students were given step-by-step instructions on how to use the NSLOM simulations and were asked to explore the different parts of the simulations. A series of controls in the control bar area allow students to change analogue input parameters. Before running the simulations and making the necessary observations, students need to determine which variables need to be changed and which should not. Each student then performed a
Newton's Second Law 𝐅𝐧𝐞𝐭 = 𝐦. 𝐚
Non equilibrium state 𝐅 ≠ 𝟎. 𝟎
𝐚 ≠ 𝟎. 𝟎
weight force
normal force
Equilibrium state 𝐅 = 𝟎. 𝟎 , 𝐯 = 𝟎. 𝟎 , 𝐨𝐫 𝐯 = 𝐜𝐨𝐧𝐬𝐭𝐚𝐧𝐭
Constant Force
series of experiments using the pre-explanation provided in the NSLOM worksheet.
Finally, students are asked to determine the mathematical relationships of NSLOM from graphs and visual representations. The simulations of Newton’s second law of motion are composed of six different simulations related to NSLOM. Figures 5-11 show screenshots of each of the six simulations. PhET allows students to interact with Newtonian representations of force and motion and lets students create their own experiments.
The simulation of force and motion was designed and developed to allow students to visualize the forces and phenomena induced by motion, so that they can get a more scientific view of the concept of force and motion, as shown in Figure 5. In the simulation, Java applet calculates force, friction, position, speed, and acceleration.
These analytic tools and graphical representations can help students grasp motion- related math.
Figure 5: Screenshot of CSs with a Visual Representation of Forces
For example, by simulating part of a force and movement (see Figures 6 and 7), students can interact with it to understand how mass affects the acceleration of a force-carrying body, balanced and unbalanced forces - causes of acceleration, force, and frictional movement.
Figure 6: Screenshot of CSs with a Visual Representation of Forces in a Horizontal Surface
According to NSLOM, the movement of the container depends on the friction (friction force) generated by the load and the tensile force (applied force) exerted by the person. These two forces have opposite directions and act on the container. Its relative size determines the movement of the container. The arrows indicate the forces applied, and students can change the attributes of the objects (such as box, refrigerator, girl, and man), and the friction force as displayed in Figure 7.
Figure 7: Screenshot of CSs with a Visual Representation of Horizontal Forces in Different Objects
The PhET simulation of the movement shown in Figure 8 shows the effect of increasing or decreasing the angle of the inclined surface, so that students can easily manipulate the angle to accurately measure the force and other factors such as friction, normal force, gravity, and objects acceleration, which are difficult to achieve in the opposite real world.
Figure 8: Screenshot of CSs with a Visual Representation of Forces in the Inclined Surface
In Figure 9, the students can create this experiment in ideal condition (non- frictional surfaces and the absence of air resistance) that are difficult to generate in the real world, by eliminating the friction and other resistive force. In addition to studying the influence of the amount and the shape of the masses on motion, as well as learners can turn friction and choose different values of the coefficient of friction. They can also change the amount of applied force and the objects (masses) to see what happens.
Figure 9: Screenshot of CSs with a Visual Representation of Forces in the Horizontal and Inclined Surface
A game of Robot is used to demonstrate the principles of NSLOM in the simulation: Robot moving company. The students can play by placing the file cabinet on the horizontal ground and then using the arrows, so that the Robot "start" to try to push the file cabinet instantly from the company to the house without letting the cabinet to slide down. They can see the force diagram during the motion (see Figure 10).
Figure 10: Screenshot of CSs with Robot Applying Forces in a Horizontal Surface
Students can make the game more challenging by placing an inclined surface.
Figure 11 shows how students would be able to move a small crate from the company to the house, by using the corrective force associated with the angle to prevent the crate from falling.
Figure 11: Screenshot of CSs with Robot Applying Forces in an Inclined Surface