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Newton’s first law of motion
An object at rest will remain at rest, and an object in motion will continue in motion with the same speed and in the same direction unless acted upon by a net external force (also known as the law of inertia)
Newton’s second law of motion
The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This can be expressed with the formula:
F = ma
The velocity of an object changes when it is subjected to an external force.
Newton’s third law of motion
For every action, there is an equal and opposite reaction. This means that forces always occur in pairs; when one object exerts a force on another, the second object exerts a force of equal magnitude but in the opposite direction on the first object.
Characteristics of scalar quantities
They are affected by magnitude only and no direction.
Characteristics of vectors quantities
They are affected by both magnitude and direction.
Examples of scalar quantities
Mass, speed, distance, energy, time
Examples of vector quantities
Displacement, velocity, acceleration, force, weight
Principle of moments
When a body is in equilibrium, the sum of clockwise movements about a pivot is equal to the sum of anticlockwise moments about the same pivot
Conditions for a body to be in equilibrium
The resultant moment on the body is zero
The resultant force on the body is zero
