CHAPTER 1: Introduction, Measurement, Estimating Answers to Questions 1. (a) Fundamental standards should be accessible, invariable, indestructible, and reproducible. A particular person’s foot would not be very accessible, since the person could not be at more than one place at a time. The standard would be somewhat invariable if the person were an adult, but even then, due to swelling or injury, the length of the standard foot could change. The standard would not be indestructible – the foot would not last forever. The standard could be reproducible – tracings or plaster casts could be made as secondary standards. (b) If any person’s foot were to be used as a standard, “standard” would vary significantly depending on the person whose foot happened to be used most recently for a measurement. The standard would be very accessible, because wherever a measurement was needed, it would be very easy to find someone with feet. The standard would be extremely variable – perhaps by a factor of 2. That also renders the standard as not reproducible, because there could be many reproductions that were quite different from each other. The standard would be almost indestructible in that there is essentially a limitless supply of feet to be used. 2. There are various ways to alter the signs. The number of meters could be expressed in one significant figure, as “900 m (3000 ft)”. Or, the number of feet could be expressed with the same precision as the number of meters, as “914 m (2999 ft)”. The signs could also be moved to different locations, where the number of meters was more exact. For example, if a sign was placed where the elevation was really 1000 m to the nearest meter, then the sign could read “1000 m (3280 ft)”. Including more digits in an answer does not necessarily increase its accuracy. The accuracy of an answer is determined by the accuracy of the physical measurement on which the answer is based. If you draw a circle, measure its diameter to be 168 mm and its circumference to be 527 mm, their quotient, representing , is 3.136904762. The last seven digits are meaningless – they imply a greater accuracy than is possible with the measurements. The problem is that the precision of the two measurements are quite different. It would be more appropriate to give the metric distance as 11 km, so that the numbers are given to about the same precision (nearest mile or nearest km). A measurement must be measured against a scale, and the units provide that scale. Units must be specified or the answer is meaningless – the answer could mean a variety of quantities, and could be interpreted in a variety of ways. Some units are understood, such as when you ask someone how old they are. You assume their answer is in years. But if you ask someone how long it will be until they are done with their task, and they answer “five”, does that mean five minutes or five hours or five days? If you are in an international airport, and you ask the price of some object, what does the answer “ten” mean? Ten dollars, or ten pounds, or ten marks, or ten euros? If the jar is rectangular, for example, you could count the number of marbles along each dimension, and then multiply those three numbers together for an estimate of the total number of marbles. If the jar is cylindrical, you could count the marbles in one cross section, and then multiply by the number of layers of marbles. Another approach would be to estimate the volume of one marble. If we assume that the marbles are stacked such that their centers are all on vertical and horizontal lines, then each marble would require a cube of edge 2R, or a volume of 8R3, where R is the radius of a marble. The number of marbles would then be the volume of the container divided by 8R3.

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Free Fall
Rachel Shea
Physics 131 Lab, QL
Hasbrouck 210
Sept. 21, 2014
Abstract
This experiment measures the study of motion by observing the force of gravity acting solely upon an object, and also measures reaction time. If an object is in free fall, the only force acting upon it is gravity. The object used in this experiment was a golf ball that provided some acceleration when dropped. A sensor positioned underneath a table recorded the golf ball’s pattern of motion, when dropped. The main objective of performing this experiment is to measure the velocity and position of the ball to eventually find the acceleration of free fall. A computer program called, DataStudio, was used to create a graph of position vs. time and a graph of velocity vs. time. The second part of the experiment involved randomly dropping a ruler and having your partner catch it to determine reaction time.
Questions
1. The parabolic curves open upward instead of downward because of the golf balls movement over time: where it is dropped from, to where it ends up. The ball begins close to the sensor, then drops to the ground, then bounces back up closer to sensor again, therefore the bounces correspond with the bottom curves of the parabola. If the data were collected from the floor then the curve would open downward. But because the sensor graphs the position from the sensor, the curve was upwards.
2.
-4572009207500
The slope of the velocity versus time graph physically...

...for 1s from 1.6m to 0.2m
it remained at rest for 2s at 0.2m
it moved in the positive direction with a constant speed for 3s’
DISCUSSIONS
I found out that the main of this experiment which is from the experiment I can say that the slope of the distance vs time graph is the velocity of the object the experiment graphs show certain properties which tells whether the object is moving in the negative direction or whether it is moving in the positive direction , if the object is at rest or if it is in motion. If the slope of the graph is increasing it means the object is moving away for the motion detector and if it is decreasing the person is moving towards the motion detector and if the slope is 0 the person is at rest
REFERENCE
Physic for engineers and scientist-serway and jewatt
...

...accident such as car crash, since the momentum changes instantly, the force becomes extremely great. Impulsive force is produced during the collision and it will cause severe damage to the car, and may also injure the passengers in it. 3 The passengers’ momentum can be stopped by objects in the car such as dashboard, side door, or windshield, however, it will cause serious injuries because the force would be very great. To increase the safety of the driver and the passengers, safety devices such as seatbelts, air bags, crumple zones, and etc. are introduced. Safety devices such as seatbelts, air bags, crumple zones and etc are designed to reduce the forces on the body if there is a collision. These safety devices are mostly made based on the physics principle of force and momentum, which is
This relationship says that if momentum is transferred over a longer period of time, the force involved is less. If the force of a collision can be reduced, then the chances that someone would get hurt in an accident are lower.4 Since momentum cannot be transformed to another form of energy, it is always conserved during any collision. The change in momentum is then a fixed quantity, and to lower the force, changes have to be made in the time of the collision.5 The time required for the car to stop in a collision have to be increased so that the forces that will impact the occupant will be lower, and they will be less likely to be hurt. If the time taken for the change...

...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...

...physics
5/23/13
Constant motion
Fill in the Blank
(constant velocity)
1)Neither( ) nor ( ) of motion changes
2)y7ui8z
Vocabulary Matching
3)
A)how fast something moves; an expression of how much time it takes for a change in position to occur; rate of motion; rate of change of position( )
B)The speed of an object in a particular direction; ratio of change in position to time interval over which change takes place.( )
C)quantity having both magnitude and direction( )
D)the separation of two points; the actual distance traveled; a scalar quantity( )
E)speed that does not change( )
F)rate of motion varies( )
G)velocity that does not change over time( )
Velocity,constant speed,average speed,distance,vector quantity,speed,constant velocity
Concept questions
4)
5)
Problem
6)A baseball pitcher throws a 30 m/s fastball toward the batter, 20 meters away. The batter hits a line drive right over the pitcher's head into center field. The fielder stops the ball 2 seconds after it is hit, 80 meters from home plate. He hesistates for 2 seconds and then throws the ball at 18 m/s to the second baseman, who catches the ball 2.2 seconds later.
a) How long does it take for the ball to travel to home plate?
b) Find the ball's average velocity on its trip from the batter to the outfielder.
c) Find the distance from outfielder to second base.
7)Two cars are moving at constant...

...Kandola
Objective:
The objective of the first part of the experiment was to derive an expression, under conditions with negligible friction, for the acceleration of a cart on a level track when it is attached by a string to a hanging mass at the end of the track. With the value of acceleration and the mass of the weight divided by the mass of the weight plus the mass of the cart, a value for free fall acceleration (g) could be determined. For the second part of the experiment, the objective was to derive a second equation for the value of constant air friction force using the known values of acceleration, free fall acceleration (g), and the various masses of the experiment.
Theory:
According to accepted physics, when an object of a larger weight pulls an object of a lesser weight there is a tension that acts between the two objects. However, even though the weights of the two objects are different, the force that each object exerts on the other is equivalent. When considering motion, acceleration is created because the system moves in the direction of the larger weight. If the mass of the larger object increases, the acceleration will also increase due to their proportional relationship. On the other hand, the force of friction acts upon the object being pulled in the inverse direction causing the acceleration to decrease. In this experiment, an object was hung at the end of a track and connected by string to an object on top...

...forces between the falling dominoes are analyzed and with this by the effect of friction has been incorporated. A set of limiting situations is discussed in detail, such as the limit of thin dominoes, which allows a full and explicit analytical solution. The propagation speed of the domino effect is calculated for various spatial separations. Also a formula is given, which gives explicitly the main dependence of the speed as function of the domino width, height and interspacing.
The energy in the next falling domino doesn't just come from the energy transferred from the domino that hits it. If that were the case, then the cascade would eventually stop. But each standing domino also contains it's own potential energy, which was given to it by it's being lifted into an unstable equilibrium by whoever set them up. This will most probably be enough to keep the cascade going for eternity.
The kinetic energy of the striking domino only has to have enough force to overcome the threshhold energy that trips the domino out of it's vertical unstable equilibrium. How much energy comes from that domino falling over is a function of the geometry of the domino and the strength of the local gravitational field. http://en.allexperts.com/q/Physics-1358/domino-effect-1.htm
Domino effect situations
Use models to compare Economy etc.
Use models to predict chain reactions like in nuclear reactions
Dynamite
Global Warming
Simple way of showing how...