Formulas for mechanical engineering principles: Stress=Force/ cross sectionalarea s = F/APa Strain = change in length/length e = x/L Young’s modulus of elasticity = stress strain E = s/ε Pa Stiffness = force/extension k = F/δ. N/m Modulus of rigidity = shear stress/shearstrain G = t/γ Pa Thermal strain = coefficient of linear expansion × …
Thermistor: A thermistor is a semi-conducting material such as mixtures of oxides of copper, manganese, cobalt, etc. in the form of a fused bead connected to two leads. As its temperature is increased its resistance rap- idly decreases. Typical resistance/temperature curves for a thermistor and common metals are shown in figure below. The resistance of …
Dalton’s law of partial pressure states: the total pressure of a mixture of gases occupying a given volume is equal to the sum of the pressures of each gas, considered separately, at constant temperature. The pressure of each constituent gas when occupying a fixed volume alone is known as the partial pressure of that gas. …
A simple anemometer consists of a small piece of wire which is heated with the help of an electric current passing through it and this material is placed in the air or gas stream whose velocity is to be measured. When the stream passing through it the wire cools it, the rate of cooling being …
What is a pressure? The pressure acting on a surface is defined as the perpendicular force per unit area of surface. The unit of pressure is the pascal, Pa, where 1 pascal is =1 newton per square metre. Thus pressure, p = F/A pascals where F is the force in newtons acting at right angles …
Speed percentage problem. A drilling speed should be set to 400 rev/min. The nearest speed available on the machine is 412 rev/min. Calculate the percentage of over-speed. Solution: Percentage of over speed= available speed-correct speed/correct speed × 100% = 412-400/400 ×100% = 12/400 × 100% = 3%
Stress-Strain Problems and solutions: A wire of length 2.50 m has a per- centage strain of 0.012% when loaded with a tensile force. Determine the extension of the wire. Solution: Original length of wire = 2.50 m = 2500 mm and strain = 0.012 100 = 0.00012 Strain ε = extension/originallength =x/L, extension x = …
UNITS AND DIMENSIONS: Units and Dimensions are used to represent the standard form of measurements for an object or a body. They are used for enhance the characteristics such as Area, Volume, Force, Density, Energy etc.of different objects in different fields. Dimensions: A dimension is a word which is used to describes the measurable characteristics …
Difference between solids and fluids: Solids and fluids are the arrangements of molecules in different patterns. This particular arrangement of molecules is different from each other. In solids, the molecules are arranged in a close and very near to each other there is no gap or space in between solid molecules. With this type of …