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Published byAntony Robinson Modified over 9 years ago
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In order to change the motion Of an object, you must apply A force to it.
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A force is the cause of an Acceleration, or the change In an object’s motion. The SI unit of force is the Newton, Labeled with an, N. Force is a VECTOR quantity!
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The Newton is a derived unit Named after the famous Isaac Newton. It is a derived unit that comes From multiplying acceleration By mass. 1 N = 1kg X 1 m/s 2
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Forces can act through contact Or at a distance. Contact forces are forces that Arise from the physical Contact of two objects. Field forces are forces that Act across a distance, not Through contact. (i.e. magnets or gravity)
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In order to show forces on paper, We use force diagrams. A force diagram is a diagram of The objects involved in a situation And the forces exerted on The objects.
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Another way of showing the Forces involved on an object Is a free body diagram. It is basically a force diagram That has only an isolated object.
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An object at rest remains at rest, And an object in motion continues In motion with constant velocity (that is, constant speed in a Straight line) unless it experiences A net external force.
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The tendency of an object not To accelerate is called inertia. The net external force is the Total force resulting from a Combination of external forces On an object; sometimes Called the resultant force.
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Inertia is directly related to The mass of the object. The greater the mass, the less The object will accelerate under A given force. Equilibrium is the state of a Body in which there is no Change in its motion.
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The acceleration of an object is Directly proportional to the net External force acting on the Object and inversely proportional To the mass of the object.
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This is much easier to write As an equation… F = ma
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FORCESYMBOLDefinitionDirection FrictionFfFf The contact force that acts to oppose sliding motion opposite the direction of sliding NormalFNFN The contact force exerted by a surface on an object Perpendicular to the surface SpringF sp The pull or push a spring exerts on an object Opposite the object at end of spring TensionFtFt The pull exerted by a string or rope when attached to a body Away from object and along string ThrustF thrust A general term for the forces that move rockets or planes Same direction of acceleration WeightFgFg A long-range force due to gravity between objects Straight down to the center of earth
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The normal force is a contact Force exerted by one object on Another in a direction Perpendicular to the surface Of contact. The normal force is always Perpendicular to the surface, Not necessarily opposite the Force of gravity.
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F = ma
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The weight of an object is The magnitude of the force Of gravity acting on that object. w = mg
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A 5.5 kg watermelon is pushed Across the table. If the Acceleration of the watermelon Is 4.2 m/s 2 to the right, find The net external force. F = 23 N to the right
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A ball is pushed off with a force Of 13.5 N accelerates at 6.5 m/s 2 to the right. What is The mass of the ball? 2.1 kg
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The constant velocity that is Reached when the drag force Equals the force of gravity is Called the Terminal Velocity. The terminal velocity of a person Out stretched is about 60 m/s!
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An interaction pair is a Pair of simultaneous equal but Opposite forces resulting from the Interaction of two objects.
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If two bodies interact, the Magnitude of the force exerted On object 1 by object 2 is equal To the magnitude of the force Simultaneously exerted on object 2 by object 1, and these two forces Are opposite in direction.
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This is better stated as For every action, there is an Equal by opposite reaction.
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When a softball with a mass of 0.18 kg is dropped, its acceleration Is g. What is the force on the Earth due to the ball, and what is Earth’s acceleration? Earth’s mass is 6.0 X 10 24 kg 1.8 N1.8 N2.9 X 10 -25 m/s
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A 50 kg bucket is being lifted by a Rope. The rope will not break if the Tension is 525 N or less. The bucket Started at rest, and after being lifted 3 m, it is moving at 3 m/s. If the Acceleration is constant, is the Rope in danger of breaking? 570 N, yes it will break!
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There are only 4 fundamental Forces of nature… Gravitational Forces Electromagnetic Forces The Strong Nuclear Force The Weak Nuclear Force
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