Topic 1: Forces around you

Newton's First Law of Motion
An object remains at rest, or moves in a straight line at constant speed, unless it is acted on by an unbalanced force 
- if two forces are equal and opposite, they are balanced 
- an object will move if forces are unbalanced
- any moving object will keep moving in the same direction without any change in speed unless another force acts upon it, making the forces unbalanced 

Defining Equilibrium
Any object that is subject to balanced forces is said to be in equilibrium 
- if an object remains at rest, it is in static equilibrium
- if the object is moving with a constant speed, it is in dynamic equilibrium 

Defining Weight
The force due to gravity close to the surface of the Earth is known as weight and has a magnitude given by:
weight = mass x acceleration due to gravity
which can be written using symbols as
W = mg 

- close to the Earth's surface, the value of g is 9.81 m s^-2 
- mass is a measure of how much matter an object is made of
- weight is the force that our planet exerts on that matter
- weight is a force, and so…