Fundamental Concepts in Science - Assignment Example

Key Concepts in Science Question One Table List of the seven main Standard International (SI) baseunits of measurement Base quantity SI base unit: Name SI base unit: Symbol Definition 1 length meter m The meter refers to the path length travelled by light over an interval of time of 1/299792458 of a second in a vacuum. 2 mass kilogram kg The kilogram refers to the unit of mass; the kilogram equals the mass of the kilogram’s international prototype. 3 time second s The second refers to the duration (interval) of 192631770 radiation periods. The radiation that corresponds to the transition amid the two hyperfine ground state levels of a cesium 133 atom. 4 Electric current ampere A The ampere refers to the constant current that if maintained in two directly parallel infinite length conductors, of insignificant circular cross-section, and located 1 meter separately in vacuum, would produce amid these conductors an equal force to 2 x 10-7 newton per length meter. 5 Thermodynamic temperature kelvin K The Kelvin, thermodynamic temperature unit refers to the thermodynamic temperature fraction 1/273.16 of the water triple point. 6 Amount of substance mole mol 1. The mole refers to the amount of a system substance that contains as many elementary (basic) entities (units) as atoms are there in carbon 12’s 0.012 kilogram. 2. When the mole is employed, the basic entities must be particular and may be molecules, atoms, electrons, ions, other particles, or particular groups of such particles. 7 Luminous intensity candela cd The candela refers to the luminous intensity within a particular direction, of a source which emits monochromatic radiation having a frequency of 540 x 1012 hertz as well as has a radiant intensity within that direction of a 1/683 for every steradian. (Barry 797-800) Question Two The SI is based on the system of metre-kilogram-second (MKS) instead of the system of centimetre-gram-second (CGS) that in turn had various variants. Therefore, there was a need to have standard units of measurement to be used conventionally, especially that the world is becoming global. In a global village there is need of communication across-cultures for ease of communication in commerce and science, the driving engines of globalization. This means that there was need to harmonize units of measurement to enable coordination between the different disciplines in the world (Barry 797). This metric system is useful in several ways. It gives a standardized way of making measurements (using standardized units of measurement globally). It bring together various organization on the international scene to forge a common definitions for SI and set rules that govern writing and presentation of measurement in a universally accepted standard way. As already mentioned this development eases coordination between the several disciplines especially in commerce and science. Other advantages of the SI units include: global adoption (they have been adopted globally) and provides a universal framework for developments and research in measurements. Question Three Table 1. List of the 12 SI derived units of measurement Derived quantity SI derived unit: Name SI derived unit: Symbol 1 area square meter m2 2 volume cubic meter m3 3 speed, velocity metre per second m/s 4 acceleration metre per second squared m/s2 5 wave number reciprocal metre m-1 6 mass density kilogram per cubic metre kg/m3 7 specific volume cubic metre per kilogram m3/kg 8 current density ampere per square metre A/m2 9 magnetic field strength amper per metre A/m 10 luminance candela per square metre cd/m2 11 mass fraction kilogram per kilogram that may be symbolized by number 1 kg/kg = 1 12 amount-of-substance concentration mole per cubic metre mol/m3 (Quinn 112-117) (Thompson and Taylor 19-22) (Barry 801-803) Question Four Hydraulic safety system In this system a power tong assembly in which a safety latch mechanism consists of a power portion equipped with two side connections of outlet, one that is linked to a control portion for controlling the cross section opening of the side connection of the tank. The power portion has a control element within the kind of a piston-shaped body value with equal magnitude surfaces on both subject end faces to the working medium pressure and with an opening running in the valve body movement direction. This opening has a conical expansion of its end of inlet flow. This blocks the direct link of the supply with tank return. Pressure and force interaction can be observed in the description of this system. In one type of control a lever valve within the unit is put on to the right through direction via pneumatic act on a cylinder. This implies that the hydraulic oil enters the working device. On reversal of the cylinder, the oil flow goes back to the tank directly. Reversing into the switch-off place is probable through a spring return connected to the lever with concurrent pneumatic cylinder unloading. Hydraulic screwing devices are usually equipped with equipment of limiting pressure that is made as an installation cartridge controlled directly for the valve unit inlet section. Normally, these valves are provided with a setting value that corresponds to the utmost working pressure. The adjustment pressure is just probable by the utilization of large instruments and is problematic to move out on site. The force of the tong screw is adapted to the prescribed values of the pipe material is obtained by pressure limitation adjustment of the remotely placed hydraulic unit (Kleppner and Kolenkow 79-84). More technical development allowed the appearance of units of screwing for which consumer unit, usually a hydraulic motor, is inadequate. These screwing units are obtained by the inclusion of lift cylinders, countertongs, process units as well as identical equipment that are in general operated hydraulically. The link of sections into the hand-controlled lever valve makes probable the operation of more functions through the screwing device the hydraulics. A utmost permissible pressure should be allocated to every function through an additional valve of pressure-limiting (Jorg and Hans-Christian 13-15). The multiplicity of actuations causes the appearance of complex pipe runs whose via sections do not match up to the incoming oil flow and therefore a main portion of the hydraulic oil, because of the building-up of pressure within the flow, with heat production, flows, via bthe major valve of limiting pressure into the return. The present units are not made for this heat load since, when operating the individual functions, the main portion’s pressure is usually decreased at the major valve of limiting pressure, whose setting match up to that of the uppermost consumer unit. Question Five The two main types of structural beams are vertical elements of beams (associated with walls in building) and horizontal elements of beams (associated with associated with roofs and floors in building). In building vertical elements are walls, beams, and lift cores among others. On the other hand, horizontal elements include trusses, slabs, and space frames among other significant beams. More specifically we have the primary beams and the secondary beams in a structure. Primary beams are the main beams connected to the columns and the secondary beams are the supporting beams mainly joined to the primary column (Serway and Jewett 15-17). Beam supports are in general categorized as free, fixed, or pinned. Beams span amid supports carrying to the external reaction forces the external load forces. The kind of support influences shear forces and bending moments’ distribution. A pinned support offers vertical, however, not rotational restraint. On the other hand, a fixed support offers vertical as well as rotational restraint. And a free support offers no restraint that might seem as a paradox (normally a free support is referred to as a free end). The kind of support considerably influences the shear forces and bending moments (Electrical Engineering Definitions 45-49). For the identical span L as well as the identical loading, say a consistently distributed load of W, shear forces and bending moments distribution is quite different. Within simple construction, it is usually assumed that beam supports are pinned. In practice it seldom to find fixed and pinned supports, however, beams simply linked to other steel beams or supported on walls are regarded as pinned. In case beams are portion of complete frames or continuous the distribution of shear forces and bending moments is influenced by the complete structure behavior. Question Six Moments refers to the ‘balancing power’ of a weight usually given by the product of that weight multiplied by the distance it is from the pivot. A force’s distance from the turning point is called the moment arm as balancing power is called the weight’s moment about the pivot. An example of a moment is having a balancing case where weights are not equal. One of the weights has to be twice the other. For them to balance the lighter one has to be exactly twice away from the pivot as the other is. The resultant balancing power of the weight is its moment. A moment is also called a torque (Electrical Engineering Definitions 44-47). When two forces say a tension and compression forces are working to counter each other although each has its own line of action they are referred to as a ‘couple’. A couple thus offers a pure to torque that is equal to either forces times the distance amid their lines of action. For example there are two parallel forces of 300 N in reverse directions that are applied to a block at points that are 0.5m apart. Take the torques about that point of application of force from one point. If there is no distance then that force provides no torque/moment. The torque is then as a result of the opposite force (Kleppner and Kolenkow 87-90). It is in the direction of the force that does not have a torque that is considered negative because of the angles. Its value is -300N x 0.5m = -150-N-m. Using the same situation and considering the toques/moments about the application point of the force that provides no torque. This means any bending is on the side that provides the torque and -150-N-m. Now take into account the torques about the block’s center point. Here every force offers torque in the same direction, however, every torque is -300N x -0.25m or -75N-m. Nonetheless, again the sum torque is -150-N-m. If we changed the point of calculating the torque the results will remain, since a couple is usually identical. Because there lacks net force within a couple, it is a pure torque. This can also be applied in a motor vehicle considering the weight from the chassis and the tires. Question Seven Electrical power refers to a measure of energy used, or electrical work, per time unit. This is explained by the Watt’s Law (Serway and Jewett 15-16). According to this law an electrical device’s instantaneous power refers to the work which is performed per unit of time. Considering the current, I, and the Voltage, V, P =IV = Joule/Second = Watt The Watt is applied in specifying that rate an electromagnetic energy is, absorbed, dissipated or radiated, or that rate at which an electrical energy is dissipated. The unit of power is W or joule/second (Electrical Engineering Definitions 44-45) Question Eight An atom consists of the following: proton (s) as positive charges, Neutron (s) as neutral charges, and electron (s) as negative cahrges. Propertities of charges are that like charges alwayss repel one another while unlike charges always attract each other, and the repulsion or attraction force conforms to the inverse square law. When an elctron moves from an atom the atom remains with a net positive charge. There is a free electron, negatively charged and a postive charge atom. The atoms bond together through an attraction and repulsion force untill they form a molecule (Quinn 117-119). Question Nine When an electron is detached from an atom through some work the atom remains positively charged and the electron is free and negatively charged. There are two options for the free electron: be captured by a close positive atom or remain free as well as migrate to the material surface that happens since like charges repel. If it remains free then the assumption is that the energy consumed in dislodging the electron from the respective atom is inadequate to fully ionize the electron in question from the material (Kleppner and Kolenkow 91). Immediately it is at the material surface the electron will: remain positioned on the surface up to the point where it will be captured by a close positive charged atom or move along the surface in case it meets an electrical field. The localized/positioned electrons release a negatively charged area or what is known as static electricity. The static example is as follows: comb via the hair, electrons are removed mechanically from the hair as well as the rest on the comb. As a result, the hair strands are charged positive, as well as stands up since the positive charges look for the most distance amid one another. And for a period of time the positive charge reduces (Kleppner and Kolenkow 92). Question Ten An Insulator is a material which limits the flow of current. Big potential variations are needed to push electrical current via these materials. They include Wood, Rubber, Plastic, glass, concrete, and paper. On the other hand, a conductor is a material that permits for the simple establishment of a current applying minimal voltage. Examples include, silver, aluminum, copper, zinc, magnesium, and potassium among other metals (Thompson and Taylor, 21-26). Question Eleven R=pL/A where R = resistance, p=resistivity, L=Length, and A= cross-sectional Area. Resistivity of copper in ohm-m (x10-8) at 20 degrees Celsius is 1.724. Resistance = 1.724 x 10-8 ohm-m x 3.0m/1.0mm = 40.376 =40.38 ohms. If the cross section area is increased to 5.0mm. Resistance = 1.724 x 10-8 ohm-m x 3.0m/5.0mm= 7.2752 =7.28 ohms (Serway and Jewett 17-18). Question Twelve circuit diagram R30Ω R45Ω R90Ω R80Ω R1200Ω 250V a) total circuit current Itotal = I1 + I2 + I3 + I4 + I5 (Serway and Jewett 17-19). =V1/R1 +V2/R2 + V3/R3 + V4/R4 + V5/R5, = 250V/30Ω + 250V/45Ω + 250V/90Ω + 250V/80Ω + 250V/1200Ω, = (30,000V + 20,000V + 10000V + 11250V + 750V)/3600Ω, =72000V/3600Ω = 20V/Ω =20A. b) Current in each resistor I1=V1/R1=250V/30Ω = 8.33A, I2=V2/R2 =250V/45Ω =5.56A, I3=V3/R3 =250V/90Ω = 2.78A, I4=V4/R4 =250V/80Ω =3.13A, and I5=V5/R5 =250V/1200Ω = 0.21. c) Voltage across each resistor Voltage across each resistor is 250V. d) Power dissipated in the 90Ω resistor Power P=IV= 2.78A x 250V= 695 Watt. Question Thirteen The Force (F) =Length (L) x flux density tesla (T)/current (A). Current = 50A, conductor 30cm in length, and 0.25 is flux density. Therefore, force (F) =30cm x 0.25T/50A =0.15N (Serway and Jewett 19-20). Question Fourteen Kinetic energy occurs whenever an object that has mass is moving with some velocity. The kinetic energy of a given object is given by the equation KE = (1/2) mv2, KE = Energy (given in Joules), m = mass (given in kilograms), and v = velocity (given in meters/second). An example of kinetic energy is everything seen moving about such as flowing water, during falling from a waterfall. Potential energy occurs whenever a given object that has mass has a place within a force field. Potential energy of a given object is given by the equation PE = mgh, PE = Energy (given in Joules), m=mass (given in kilograms), g = the earth’s gravitational acceleration (given in 9.8m/sec2), and h = height above the surface of the earth (in meters) (Serway and Jewett 21-22). An example of potential energy in daily life is the place of objects in the gravitational field of the earth such as water at a waterfall’s top, prior to the precipice. Question Fifteen A DC signal always has a constant voltage as well as current, ignoring the changes happening during power off and power on. The frequent sources of DC signal are batteries and DC power supplies. V = constant and I – constant. t AC signal or alternating current refers to a fluctuating current which is associated with altering potential difference (AC Voltage). Most frequently the alternating current pattern is linked with a sinusoidal alteration in Voltage. The frequent sources of AC signal are signal generator and household power. V (t) = A sin (2π ft), The Peak and the peak-to-peak RMS (Serway and Jewett 23). t Works Cited Barry, N Taylor. "The Current SI Seen From the Perspective of the Proposed New SI." Journal of Research of the National Institutue of Standards and Technology (2011): 797-807. Print. Electrical Engineering Definitions. Electrical Engineering Definitions. London: John Willey & Sons, 2012. Pp. 44-57. Print. Jorg, Schulze-Beckinghausen and Bock Hans-Christian. "Hydraulic safety interlock system ." Patent Library (2012): 13-22. Print. Kleppner, Daniel and Robert J Kolenkow. An introduction to mechanics. Cambridge: Cambridge University Press, 2010. Pp. 78-92. Print. Quinn, Terry. From artefacts to atoms: the BIPM and the search for ultimate measurement standards. Oxford : Oxford University Press, 2012. pp. 112-121. Print. Serway, Raymond A and John W Jewett. Physics for Scientists and Engineers. London: Brooks/Cole Cengage, 2010. Pp. 15-23. Print. Thompson, Ambler and Barry N Taylor. The International System of Units (SI) (Special Publication 330). Gaithersburg, MD: National Instititute of Standards and Technology, 2012. Pp. 19-32. Print. Read More