Forces

1. Newton's 3rd Law

1.1. For every action there is an equal and opposite reaction

1.2. Action and reaction act on different objects

2. Newton's 1st Law

2.1. 1) An object at rest would remain at rest

2.2. 2) An object in motion will continue to be in motion at a constant speed in the same direction

2.3. In the absence of a net force (i.e. forces are balanced)

2.3.1. For example...

2.3.1.1. A rock on a table

2.3.1.1.1. The rock's weight is pushing down on the table

2.3.1.1.2. The table's reaction force pushes it back (3rd law)

3. Newton's 2nd Law

3.1. The resultant forces acting upon an object is equal to the product of the mass and the acceleration of the object.

3.1.1. Basically, F=ma

3.1.1.1. SI unit for force: newton (N)

3.1.1.2. 1N = 1kg m s^-2

3.1.2. The direction of the force is the same as the object's acceleration

3.1.3. The direction of the free body is dependent on the resultant force

4. Turning Effect of Forces (Moments)

4.1. Is the product of

4.1.1. Force

4.1.2. Perpendicular distance

4.2. Can be

4.2.1. Clockwise

4.2.2. Anticlockwise

4.3. Rotational equilibrium

4.3.1. sum of anticlockwise moments = sum of clockwise moments

5. Frictional Forces

5.1. Created whenever two surfaces move or try to move across each other

5.2. Always opposes the motion or attempted motion of one surface across another surface

5.3. Is dependant on the texture of both surfaces