Everything has a force. For example, a car on a road has a driving force pushing it forward and friction and wind resistnce pushing it back. If the driving force is larger, we say the resultant force is larger, causing the car to accelerate.
Newton's first law: Objects either stay at rest or remain in uniform motion unless acted on by a force.
This means that an object will be at a constant velocity until a force acts on it, causing it to either change direction or speed.
Newton's second law: Force is proportional to mass and acceleration.
This gives us the equation F=ma where F = resultant force (N), m = mass (kg) and a = acceleration (ms^-2)
Newton's third law: Every action has an equal or opposite reaction.
This means that every force acting on something has a force acting back. When we sit on a chair we exert a force downwards. The chair has to exert the same force upwards to not fall through.
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