Cie igcse 0625 physics revision 2017 and 2018

1.general physics  1.1 length and time  -i-Physical Quantity Physical Quantities A physical quantity is a property of an object that can be measured with a measuring instrument. A physical quantity is usually expressed as “a magnitude ( numerical value)  and a  physical unit or more ” Example :- Normal body temperature of a healthy human being is  37  0 C -ii-Length Measuring Length. Length is “the distance between two points in a space”. According to SI units, the length quantity is expressed in meter. There are several kinds of measuring devices used to measure quantity of length, among others, are as follows. Tools used… a-   Measuring tape. b-   Ruler c-   Vernier callipers. d-    Micrometer Measurement of length Length is measured accurately through many meth...

Speed Speed can be defined as the distance covered by a moving object in unit time taken. Speed is a  scalar quantity  and hence it can only be represented by magnitude not by direction.In other words, “ The speed of an object can also be considered as the magnitude of the velocity of the object ”.  Speed Formula : Speed =  D i s t a n c e   c o v e r e d T i m e   t a k e n   X =  d t   where,  X  = speed of the moving object;  d  = distance traveled by the moving object;  t  = time taken to travel distance ‘d’.  Formulas for finding area, gradient and acceleration are mentioned in image below. acceleration and deceleration are related to changing speed 

MASS AND WEIGHT AND DENSITY Weight  = force of gravity = mass x free fall acceleration = ma = mg Force = Weight = mg   the acceleration of free fall for a body near to the Earth is constant Notes:- 10 m/s 2  = 10 N/kg   Weight is the force which causes an object to accelerate downwards and has the value mg. The value of the acceleration caused by weight can be calculated from Newton’s second law, using the equation F = ma Weight unit is N (because it is a force) It is measured by spring balance   Mass     Weight Define It is the amount that body contains“It is not a force” It is the force of gravity acting on the body“It is a force” Units kg N  (kg.m/s 2 ) Scalar or vector Scalar quantity(No direction) Vector quantity(always vertical downwards) Device used to measure Pan  balance.Beam balance. Spring balance Dependence on place Mass of a body remains the same throughout the universe (doesn’t change from one...