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Forces - Coggle Diagram
Forces
The speed of a moving object is rarely constant. When people walk, run or travel in a car their speed is constantly changing. The speed that a person can walk, run or cycle depends on many factors including; age, terrain, fitness and distance travelled.
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Newtons Laws
Newtons First Law
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the object is moving – the object will continue to move at the same speed and in the same direction. So the object continues to move at the same velocity.
So, when a vehicle travels at a steady speed the resistive forces balance the driving force.
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Newtons Second Law
The acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object.
As an equation: F = ma
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For everyday road transport; estimate the speed, accelerations and forces involved in large accelerations.
Newtons Third Law
Whenever two objects interact, the forces they exert on each other are equal and opposite.
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A number of forces acting on an object may be replaced by a single resultant force that has the same effect as all the original forces acting together.
A single force can be resolved into two components acting at right angles to each other - use Pythagoras’ theorem on forces.
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Weight is the force acting on an object due to gravity. The force of gravity close to the Earth is due to the gravitational field around the Earth.
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When a force causes an object to move through a distance, work is done on the object.
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The extension of an elastic object, such as a spring, is directly proportional to the force applied, provided that the limit of proportionality is not exceeded. Hooke’s Law
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A force that stretches (or compresses) a spring does work and elastic potential energy is stored in the spring. Provided the spring does not go past the limit of proportionality the work done on the spring and the elastic potential energy stored are equal.
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A force or a system of forces may cause an object to rotate. The turning effect of a force is called the moment of the force.
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Work done against the frictional forces acting on an object causes a rise in the temperature of the object.
Elastic deformation occurs when an object returns to its original shape and size after the forces are removed. An object that does not return to its original shape after the forces have been removed has been inelastically deformed.
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An object floats when its weight is equal to the upthrust.
An object sinks when its weight is greater than the upthrust.
An object less dense than the surrounding liquid displaces a volume of liquid equal to its own weight. So the less dense object will float.
An object denser than the surrounding liquid is unable to displace a volume of liquid equal to its own weight. The denser object sinks.
The atmosphere is a thin layer of air round the Earth. The atmosphere gets less dense with increasing altitude.
Air molecules colliding with a surface create atmospheric pressure. The number of air molecules above a surface decreases as the height of the surface above ground level increases. So atmospheric pressure decreases with an increase in height.
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If an object is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot.
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