Forces , energy conversion (sci sec2)
Forces - contact forces, non-contact forces.
contact forces - frictional force, elastic force such as;
frictional force : generates heat when two objects rub against each other. friction allows heat generation, allow things to move, allow things to stop (eg: a pen not dropping)
elastic force: stretching a rubberband, spring
non contact forces - gravitational force, magnetic force such as;
gravitational force : focuses on weight (N) , force exerted by earth on an object pulling it towards its center called weight.
Magnetic force ; force exerted between a magnet and another magnet / magnetic material ,, likes poles repel and unlikepoles attract
Mass and weight are both two different things,
Mass- measured in kg , constant EVERYWHERE , its the amount of matter in a certain object.
Weight - measured in the SI nit of Newton (N) , it varies on the location. Must use the formula WMG ( mass x gfs ) to find weight. → usually Gfs on earth is 10 N/kg
Pressure- atmospheric pressure
its when two things interact
is force per unit area
Factors affceting pressure :
-surface area. ( Smaller surface = more pressure , Bigger surface = lesser pressure )
Formula to find pressure(Pa) = area x force(N)
Work Done (J) - the object moves in the same direction as the force applied on it
SI unit : Joule (J) → applies for KE , GPE
Formula to find WD : force(N) x distance(m)
🇦 (energy cannot be created or destroyed)
:: the different forms of energy → sound , potential , electric , kinetic , thermal energy , light
Kinetic energy(J) → is when an object / person is moving
Formula to find KE = ½ x mass(kg) x speed (v)square
Gravitational potential energy (J) → energy posessed by a body due to its position
Formula to find GPE = mass(kg) x gfs(10N/kg) x height(m)
The total is always constant , GPE depends on the location , when at the highest point , the amount of KE is at 0J and when at the highest point the amount of GPE is more than 0J.