Young Modulus of Copper
Physics TAS Young Modulus of Copper Objectives -Determine the Young modulus of copper by simple experiment -Study the relationship of strain and stress between elastic and plastic deformations of copper -Verify a wire will not return to its original length after certain extensions Preview Questions .Hooke's Law states that the elastic force is directly proportional to the extension (or compression) of the elastic body. A wire obeys Hooke's Law only if it is within its elastic limit. 2.Elastic deformation means a stretched wire will return to its natural length. If the wire is stretched beyond its elastic limit, it will not return to the original length and will make permanent extensions. This is called plastic deformation. 3.A longer wire will extend more than a shorter wire of the same cross-sectional area under the same applied force. 4.As in Q.3 , force constant can be easily affected by geometric factors such as length and cross sectional area. But the stiffness of materials depends on their Young modulus only, which is not affected by geometric factors. So force constant is not a good quantity to compare the stiffness of materials. Apparatus Copper wire ..................1 roll slotted mass with hanger 100g hangers ....................1 100g slotted mass .........~15
Sir Isaac Newton.
Isaac Newton's life can be divided into three quite distinct periods. The first is his boyhood days from 1643 up to his appointment to a chair in 1669. The second period from 1669 to 1687 which was the highly productive period in which he was a professor at Cambridge University. The third period (nearly as long as the other two combined) saw Newton as a highly paid government official in London with little further interest in mathematical research. Isaac Newton was born in the manor house of WoolsThorpe, near Grantham in Lincolnshire. By the calendar in use at the time of his birth he was born on Christmas Day 1642. Isaac Newton came from a family of farmers but never knew his father, also named Isaac Newton. Although Isaac's father owned property and animals, which made him quite a wealthy man, he was completely uneducated and could not sign his own name. Isaac's mother Hannah Ayscough remarried Barnabas Smith the minister of the church at North Witham, a nearby village, when Isaac was two years old. The young child was then left in the care of his grandmother Margery at Woolsthorpe. Basically treated as an orphan, Isaac did not have a happy childhood. His grandfather James was never mentioned by Isaac in later life and the fact that James left nothing to Isaac in his will, made when the boy was ten years old, suggests that there was no love lost between the two. There is
Explain how excessive exposure to radiation can cause harm.
M4 – Explain how excessive exposure to radiation can cause harm. The amount of radiation given to patients in diagnosis is dependent on how close vital organs and tissues are to the malignant tumour, there are two terms commonly used by scientists when dealing with radiation doses, absorbed dose, the amount of energy received by a mass of tissue, which is measured in kilograms (Kg), It has the unit J/Kg and is called the gray (Gy). Effective dose, if the ionising radiation types are compared using the same amounts of energy, alpha particles cause much biological damage, 20 times more damage than X-rays. In medicine radiation affects different tissues and organs in different ways and so each tissue or organ has a number which is used as a quality factor, the absorbed dose is multiplied by this number to give the figure for effective dose, also measured in J/kg b called Sievert (Sv). Major effects of ionising radiation on the body Injury to living tissue results from the transfer of energy to atoms and molecules in the cellular structure. Ionizing radiation causes atoms and molecules to become ionized or excited. These excitations and ionizations can: . Produce free radicals. 2. Break chemical bonds. 3. Produce new chemical bonds and cross-linkage between macromolecules. 4. Damage molecules that regulate vital cell processes (e.g. DNA, RNA, proteins). The cell can
Bouncing balls
Planning (P) For my physics coursework, I have been asked to investigate the factors, which affect the way in which a ball will bounce. I looked into a few different factors, including height of the ball, landing surface of the ball, and in depth, the height from which the ball is bounced. I also looked at how the temperature change takes place while bouncing the ball. I took my final point further and decided to investigate the temperature of the ball while bouncing. My input variable is going to be the temperature, which I will be changing. Prediction: After doing some background research on different types of balls, I found out a reason why balls actually bounce. All balls bounce because of the air and gravity. The air makes the ball bounce. If I bounce a ball in the air, it will not stay up and bounce back down. The reason for this is gravity. If I bounce the ball hard, it will go up high in the air but if I bounce the ball softly, it will not really bounce at all. The reason for this is because balls have elastic in them. ("The elasticity is an objects property of changing shape when the deforming force is moved"). When an elastic ball is bounced on a hard surface, the shape of the ball deforms and the kinetic energy is converted and stored as potential energy. But when the ball returns to its original shape, potential energy is reconverts back to kinetic energy,
Centripetal motion. The objective of this experiment is to verify whether the tension in a centripetal force apparatus is equal to the weight of the mass.
Physics Laboratory Report Centripetal motion Aim of experiment: The objective of this experiment is to verify whether the tension in a centripetal force apparatus is equal to the weight of the mass. Theory: (Fig. 1) Fig. 2 shows an object of mass m moving with constant velocity v in a circular path of radius r. By keeping the angular speed of the rubber bung constant and considering the equilibrium of all the applied forces in the system, the theoretical value of the centripetal force F is calculated as follows: F = mv2/r or F = mr?2 where v and ? are the linear and angular speeds of the object respectively. Nevertheless, some correction should be made in this experiment. In this experiment, the following set-up is used. (Fig.2) As shown in Fig.3, in reality, the string is not horizontal and moves in a circle of radius r = l sin?. The weight of the hanger with slotted mass gives the tension (T) in the string. (Fig.3) The horizontal component of the tension provides the net centripetal force. Therefore, T sin? = mr?2 T sin? = m(l sin?)?2 T = ml?2 Apparatus: Rubber bung x 1 Glass tube (15cm long) x 1 Nylon thread (1.5m) x 1 Slotted mass (50g) x 4 Hanger (150g) x 1 Paper clip x 1 Meter rule x 1 Stop watch x 1 Adhesive tape x 1 Balance x 1 Procedures: . The mass of the rubber bung (m) was weighed and recorded. 2. The centripetal
Investigating motion using video processing software.
Experiment 6: Investigating motion using video processing software Part 1 Method The web camera was setup with the laptop connected. The web cam made a recording of firstly, a ball being thrown in the air next to a vertical ruler. On the computer program, from frame to frame the position of the ball is recorded. A displacement-time graph is produced from this data. Results Time (secs) Height (m) Speed (m/s) 0 0.057 0 0.03 0.133 2.53 0.07 0.26 3.18 0.1 0.38 4.00 0.14 0.51 3.25 0.17 0.615 3.50 0.2 0.702 2.90 0.24 0.793 2.28 0.27 0.865 2.40 0.3 0.927 2.07 0.34 0.97 .08 0.37 .006 .20 0.4 .032 0.87 0.44 .05 0.45 0.47 .057 0.00 0.5 .05 0.23 0.54 .025 0.62 0.57 0.999 0.87 0.6 0.963 .20 0.64 0.909 .35 0.67 0.84 2.30 0.71 0.767 .83 0.74 0.688 2.63 0.77 0.586 3.40 0.81 0.477 2.73 0.84 0.365 3.73 0.87 0.235 4.33 0.91 0.079 3.90 Also see graphs This graph shows a of squash ball thrown up vertically in the air. The period T is 0.91 secs. As the ball is thrown it reaches a peak being 1.057m, the displacement then decreases as gravity acts on the ball. If tangents are drawn, the gradient for the steep incline of displacement on the left side of the graph = 0.865 / 0.27 = 3.20 This gradient also calculates the mean speed, as speed = dis. / time. Thus the mean speed from 0 - 0.27 secs =
The Physics of Windsurfing
INTRODUCTION You glide across the surface of the water at unbelievable speeds, steer towards a white capped wave, and then lift off like a bird, each muscle resisting against the force of the wind. Then you smash into the trough of the wave, leap up from near disaster, and look quickly for the next wave so you can do it all over again. This is the exciting sport of windsurfing. THE BEGINNING Windsurfing began in the '60s when an aeronautical engineer and a scientist had a discussion. In 1969, the engineer presented an idea entitled "Wind Surfing: A New Concept in Sailing." This new concept involved releasing the mast from its fixed vertical position and allowing it to turn around its base (Now a days the vertical positioning is not fixed) The sailor then can both steer and balance the board through correct movements of the mast and sail. The early Windsurfer boards measured 12 feet (3.5 m) long and weighed 60 pounds (27 kg). WHAT IS A SAILBOARD? A sailboard is composed of a board and a rig. There is variation in modern sailboards; they generally range from 8 to 12 ft (2 to 4 m) and weigh between 7 to 18 kg; some have attained speeds of over 40 knots CONTROL AND MOVEMENT There is lower pressure on the forward part of the sail and a net force perpendicular to the sail. The net force propels the windsurfer, but part of this force is to the side of the sailboard. The
Evaluating a Torsional Pendulum experiment
Evaluation: I will firstly work out the overall experimental error and how far it was from the true value, using the same formula used in the preliminary. =2? = 10.36 Therefore the total error from what the true value should be is [(11.368-10.36)/11.368] x 100= 8.89% This shows that my experimental results had an overall 8.89% error, where as in my preliminary I had an error of 15.89%, therefore I believe my improvements have improved the accuracy of my results. From the 2 graphs above I can see that the result for 0.1 meter length seems to be the furthest away from the line of best fit, and may be considered as an anomalous result, however I don't think it's necessary to remove this result. The reason for this error could be any of the ones stated below, or possibly as it was the first reading I took, there could have been an initial fault in my experiment set up. Even though I have improved the accuracy of my experiment there are still many errors which will have decreased the accuracy of my results. I will now state each one and estimate percentage errors for the reading error and also experimental error if possible. * The meter ruler is accurate to ±0.5mm, therefore error on the smallest length would be (0.5/100)x100=0.5% and largest length (0.5/500)x100=0.1% . Therefore the error here can be no greater than 0.5%, so this is not a very significant error. However
Torsional Pendulum Preliminary experiment
A2 Physics Coursework Aim: To investigate a Torsional Pendulum. Research and equations: As we are working in circular motion, rather than linear motion, the equations that will help me investigate the Torsional pendulum will have to be derived. Here is how it is derived. Using Force= Mass x Acceleration which is what you use for linear motion, this becomes Torque=Moment of Inertia x Angular acceleration. Using Force= -kx from a simple pendulum, this becomes Force=- Torsional Constant x Angular displacement Therefore This can definitely be compared to a=-?2x and becomes However therefore I then found out the exact expression which allowed me to directly work out I and K. The moment of inertia was simply mL2 However for the Torsional constant I first found the formula for the polar moment of inertia which was Ip=?d4/32 and the angle of twist ?=TL/GIp this was rearranged to T= GIp/L where T is the Torsional constant, then substituting in Ip I got Torsional constant= Using the equation I can now substitute in expressions for I and K to get an overall equation which came out to be: T=2? T=Time Period I=Moment of Inertia of the bar L=Length of wire G= Shear Modulus of material d= diameter of wire The following web pages were used to help me derive these equations: http://www.engin.umich.edu/students/ELRC/me211/me211/flash/tors_derivation15.swf
Task- To make a model sycamore seed that can fly easily and stay in the air so in real life it would have the best chance to be carried away.
Sycamore Seed Experiment Task- To make a model sycamore seed that can fly easily and stay in the air so in real life it would have the best chance to be carried away. Aim In this investigation I have been asked to find out how long it takes for a paper helicopter to fall 2 metres. After doing this I shall investigate other ways of changing the timing of its landing. I shall do this by using a range of variables. These include of: Ÿ Length of wings Ÿ Number of tails *I have chosen to use the variable of the number of paperclips being added to the tail of the paper helicopter that I shall make. The gravitational force, which pulls the object downwards, is called the weight of the object. Isaac Newton stated that there is a gravitational force of attraction between any two objects with mass, which depends on their masses, and the distance between them. I think with this information I can easily say that by adding more and more paperclips on to the tail of the paper helicopter it will gain more weight, which will cause the gravitational force to pull it downwards rather than upwards as there is a bigger mass pulling it downwards. I also chose to use this variable instead of changing the length of the wings because I thought that it would have a much more affective difference in the timing of its landing. *In this investigation in order to get the best results