Newtons laws

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• Newtons laws
• Inertia
• Inertia is how hard it is to change the motion of an object.
• A large object with a large mass  will find it very difficult to move, accelerate, decelerate or change direction quickly, because it will have a large inertia.
• 1st law
• Forces are balanced – object remains stationary/has constant velocity.
• A body will remain at rest, or continue to move with a constant velocity, unless acted upon by an external(resultant) force.
• Resultant force
• Resultant force is the overall force acting on an object.
• All forces have a direction (unless they’re zero) and are measured in Newtons (N).
• If forces act in the same direction add them. If forces are in opposite directions subtract them.
• If the resultant force is zero then the forces are balanced.l
• 2nd law
• Acceleration is directly proportional to resultant force.
• Resultant Force = Mass x Acceleration
• F = m x a
• Mass and Weight
• Mass and weight are NOT the same thing! Make sure you know the definitions.
• Mass- is measured of how much 'matter' an object has, its measured in kg
• Weight is a measure of how large the force of gravity is on an object, its measured in  N
• Weight is calculated by: Weight = mass x gravitational field strength W = m x g
• 3rd law
• Equal and opposite actions.
• In an interaction between 2 objects (A and B) the force exerted by object A on object B is equal and oppositeto the force exerted by object B on object A.
• Interaction pairs act on different objects so the DO NOT cancel out! We can draw them as free body diagrams.