High power electrical appliances are those which draws high current. The thinner the wire (smaller cross-sectional area), the higher the resistance of the cable which brings the current into the electrical appliances.   More thermal energy will be generated due to this higher resistance in the cable. The cable might be too hot or catch fire. So it is advisable to have thicker cables for high power electrical appliance as thicker cables have lower resistance.

Density is the mass per unit volume . Common units for density are g/cm3 or kg/m3 . SI unit is kg/m3 . Density of a pure substance is fixed, regardless of it’s size! Floating and Sinking A denser (heavier) substance will sink in liquid which is less denser (lighter). A less dense (lighter) substance will float in a liquid which is denser . If substance has the same density as the liquid, it will be suspended in the liquid.

For Combined Science Physics Olevel, when constructing vector diagram, a method called  Parallelogram Method is commonly used. Parallelogram Method is used when 2 forces are known , and the resultant (net) force R , can be found. Below show 5 different variations of questions when can be solved by using Parallelogram Method: (A) Body has acceleration , forces are unbalanced , there is a resultant force R (Newton’s 2nd law) (B) Body at rest , all forces are balanced , there is no resultant force R (Newton’s 1st law) (C) Body moving at constant velocity , all forces are balanced , there is n o resultant force (Newton’s 1st law) (D) Finding unknown force (with  resultant force R  + another known force are given ) (E) Vector diagram is applicable to all vector quantities (with magnitude and direction). Not just for forces.