# Physics

Pages: 9 (2266 words) Published: December 8, 2013
﻿Experiment 2: Kinematics of Human Motion

Abstract

Kinematics is the branch of classical mechanics that describes the motion of bodies and systems without consideration of the forces that cause the motion. There are four activities done in this experiment, graphical analysis of human motion, where displacement vs. time and velocity vs. time were graphed. Graphical analysis of motion where in the 10th seconds the total displacement is 14.69m, average velocity is 1.47 m/s. Reaction time where one of the normal reaction time among the group is 0.4s and the reaction time while someone is distracting the member is 0.5s, and lastly graph matching.

1.Introduction
All of us have the ability to move. Knowing how to describe motion is an important first step in understanding the underlying physics that governs changes in motion. We see changes in motion all the time, as we go to work or school, participate in sports or even wander around our homes. If we never changed our own motion, we would never make it out of bed in the morning. The study of motion and of physical concepts such as force and mass is called Dynamics. Kinematics is one of the topics under dynamics. Kinematics describes motion without regard to its causes. In this experiment, kinematics focuses in one dimension: a motion along a straight line. This kind of motion, involves velocity, displacement, and acceleration with regards to time. The objectives of the experiment are to draw the displacement versus time graphs and velocity versus time graphs for uniform motion and uniformly accelerated motion, and to determine one’s normal reaction time and his reaction time while being distracted by others.

2. Theory
Kinematics is a branch of mechanics that deals with the concepts needed to describe a motion regardless of its cause (Serway and Vuille, 2011). The motion of an object is the focus of kinematics including its factors such as acceleration and velocity. A velocity is a vector quantity having the ratio of distance over the elapsed time travelled plus its direction. On the other hand, Acceleration is the change in velocity over time. In the experiment, these two important terms were applied together with its formulas: Fig. 1: Velocity and Acceleration Formulas

Source:http://www.mash.dept.shef.ac.uk/Resources/em1_9constantaccelerationequations.pdf

Where:
v= Final velocity
vo = Initial velocity
a = acceleration
t= time
x = distance on a horizontal level
A free falling body is a motion of an object towards the earth’s ground with the influence of gravity alone (Serway and Vuille, 2011). Therefore the object has a constant acceleration due to its gravity, g = 9.8 m/s2. The formulas used in a free falling object is the same with the general formula (figure 1) from the velocity and acceleration however it differs only with the value of acceleration since it has a constant value of 9.8 m/s2. When the object is thrown up and down, we would refer a coordinate system with a positive y-axis pointing up and perpendicular to the earth’s surface, then value of the acceleration is turned negative and thus the x becomes y:

Fig. 2: Free-falling body Formulas
Source:http://theory.uwinnipeg.ca/physics/onedim/node8.html

Where:

v= Final velocity
vo = Initial velocity
g = acceleration due to gravity (9.8m/s2)
t= time
y= distance on a vertical level

Another activity done in this experiment was to measure the reaction time of a certain individual using a meter stick. Reaction time is the time measured for one to react to a certain event. The formula in computing the reaction time is

Where:
h = distance the meter stick has fallen measured from the 50 cm mark to where the meter stick was catched g = Acceleration due to gravity (9.8 m/s2)
t= reaction time

3. Methodology

The entire experiment was divided to four (4) activities namely, Graphical Analysis of Human Motion, Graph Matching, Graphical Analysis of Motion, and Reaction...

References: Jacobson, S. H., & Robbins, M. J. (2010). Study: Cell-phone bans while driving have more impact in dense, urban areas. Retrieved December 8, 2012 from http://phys.org/news184945487.html
Melissinos and Napolitano. 2003. Experiments in modern physics. Academic Press, USA: Elsevier Science.
Serway,R. & Vuille, C. (2011). Physics: Fundamentals. (Vol 1). Philippines: Cengage Learning Asia.
Serway, R. & Vuille, C. (2012). Physics Fundamentals I. Hiyas Press Inc., Philippines.
[Physics]. Retrieved Dec 8, 2012, from: http://www.mash.dept.shef.ac.uk/
Resources/em1_9constantacceleratio nequations.pdf.
[Physics]. Retrieved Dec 8, 2012, from: http://theory.uwinnipeg.ca/physics/o nedim/node8.html