Senior Secondary Physics (312) PDF

Senior Secondary Course Learner’s Guide, Physics (312) 1 UNITS, DIMENSIONS AND VECTOR Quantity unit...

Senior Secondary Course Learner’s Guide, Physics (312) 1 UNITS, DIMENSIONS AND VECTOR Quantity unit Symbol Length Meter m Physics: Scope and Excitement Mass Kilogram Kg  The scope of Physics is very wide Time Second s and it covers a vast variety of Electric ampere A natural phenomena. current  It includes the study of mechanics, Temperature Kelvin K heat and thermodynamics, optics, Luminous Candela Cd waves and oscillations, electricity intensity and magnetism, atomic and nuclear Amount of mole Mol physics, electronics and substance communication etc. Unit of Measurement Mass:  The laws of physics are expressed The SI unit of mass is kilogram. It is the in terms of physical quantities such mass of a particular cylinder made of as distance, speed, time, force, platinum-iridium alloy. volume, electric current, etc. For measurement, each physical Length: quantity is assigned a unit. The SI unit of length is metre. One metre is defined as the distance travelled by light The SI Units in vacuum in a time interval of  The name SI is abbreviation for 1/299792458 second. Système International d’Unitésfor Time: the International System of units One second is defined as the time required  Standards of Mass, Length and for a Cesium - 133 (133Cs) atom to Time undergo 9192631770 vibrations between two hyperfine levels of its ground state. Significant Figures Digits in measurement that are known with certainly plus the first uncertain digit are called significant figures. 1 Physics (312)  Senior Secondary Course Learner’s Guide, Physics (312)  All non-zero zero digits are significant.  Derivation of units of a physical For example, 315.58 has five quantity significant figures  All zeros between two non-zero non Vectors and Scalars digits are significant. For example, A scalar quantity has only magnitude; no 5300405.003 has ten significant direction. figures.  All zeros which are to the right of a A vector quantity has both magnitude and decimal point and also to the right direction. of a non-zero zero digit are significant. Representation of Vectors For example, 50.00 has four significant figures A vector is represented by a line with an  All zeros to the right of a decimal arrow indicating its direction. point and to the left of a non-zero non 𝐴⃗ digit in a decimal fraction are not significant. For example,.00043 Addition of Vector has only two significant figures but 2.00023 has 6 significant figures If two vectors are represented in magnitude and direction by the two sides  All zero to the right of last of non non- of a triangle taken in order, the resultant is zero digit are significant, if they represented by the third side of the triangle come from some measurement. taken in the opposite order. This is called  The number of significant figures triangle law of vectors. does not vary with the change in unit. 𝑅⃗ = 𝐴⃗ + 𝐵⃗  In a whole number all zeros to the right of the last non zero number are not significant, for example 5000 has only one sig significant figure. Derived Units Subtraction of Vector It is a unit that results from a mathematical 𝑅⃗ = 𝐴⃗ + (−𝐵⃗) combination of SI base unit. Applications of Dimensions (or dimensional equations)  Derivation of a relationship between different physical p quantities (or formula).  Checking up of accuracy of a formula (or relationship between different physical quantities).  Conversion of one systemstem of units into another. 2  Senior Secondary Course Learner’s Guide, Physics (312) Multiplication of Vectors B. Nm-2 C. J Scalar Product of Vector D. No units The scalar product of two vectors A and B 4. Two forces 20 N and 5 N are is written as A.B and is equal to AB cosθ, acting at an angle 200 below where θ is the angle between the vectors. magnitude of resultant force. A. 18.03N The scalar product of two vectors is a B. 18.0 N scalar quantity C. 17.0 N Vector Product of Vectors D. 16.5N 5. Length of (A+B) if A =3𝚤̂ + 2𝚥̂ The vector product of two vectors A and B and B= 𝚤̂ − 2𝚥̂ + 3𝑘 is written as A×B and is equal to AB sinθ, A. 4 where θ is the angle between the vectors. B. 3 The vector product of two vectors is a C. 5 vector D. 7 Unit Vector STRETCH YOURSELF Unit vector has unitary magnitude and has a specified direction. It has no units and no dimensions.  All constants are dimensionless? Explain, 𝐴⃗ what types of quantity is 𝐴= |𝐴| Avogadro’s number.  Is the commutative and associative law applicable CHECK YOURSELF to vector subtraction? Explain  The velocity of sound in air is 332m/s if the unit of length is km and unit of time is hour. What would 1. Significant number in be the value of velocity? 42003042.02 is A. 15 B. 10 C. 7 D. 5 Answer to check Yourself 2. Dimension of Kinetic energy A. ML-1T-2 1B) 2D) 3D) 4A) 5C) B. M2L2T-2 C. MLT-2 D. ML2T-2 3. SI unit of strain is A. Nm-1 3 Physics (312)