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Motion. Event that involves a change in the position or location of something. Definition. Motion is Relative. Relative – it is described compared to a REFERENCE POINT. Types of Motion. Uniform motion - constant speed in a straight line
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Event that involves a change in the position or location of something. Definition
Motion is Relative • Relative – it is described compared to a REFERENCE POINT
Types of Motion • Uniform motion - constant speed in a straight line • Accelerated motion – motion that is changing in speed or direction • Circular motion - speed is constant but the direction of motion is changing continuously
Scalar Quantities • Show magnitude [amount] only • Speed, time, temperature
Vector Quantities • Show magnitude and direction • Velocity, acceleration, force • May be graphically represented • Arrows
SpeedAverage Speed • Comparison of time and distance • A scalar quantity [magnitude only] • Distance traveled per unit time • S = d / t • T = d / s • D = s x t
SpeedInstantaneous Speed • Speed at any instant
SpeedConstant Speed • Speed that does not change • Instantaneous speed that does not change
Velocity • Speed AND direction • A vector quantity [magnitude & direction]
Acceleration • A change in velocity • Speeding up • Positive acceleration • Slowing down • Negative acceleration • Deceleration • Changing direction
Forces • Pushes or pulls • May cause acceleration [changes in motion] • May also cause changes in shape
Balanced Forces • All forces acting on an object are equal • There is no motion
Unbalanced Forces • All forces acting on an object are not equal • One or more force is stronger than others • Motion occurs
Net Force • The sum of all forces acting on an object • A net force of 0 • No motion • A net force of more than 0 • Motion occurs
Resultant • Another term for net force
Friction • Force that slows down motion • Air resistance creates friction in most situations
Gravity • Force that attracts all objects toward each other • More mass = more gravity • Acceleration because of gravity is 9.8 m/s/s • All objects accelerate at the same rate
Newton's Laws • Describe motion and changes in motion
First Law of Motion • Law of inertia • Objects at rest [not moving] will not begin to move until a force acts on them • Objects in motion will not stop moving until a force acts on them • Objects with more mass have more inertia • Bigger objects are harder to start and stop
Second Law of Motion • Law of acceleration • A force is needed to change motion • Objects accelerate in the direction of the force • The more force applied, then more acceleration • The more mass an object has, the more force is needed to accelerate the object
Third Law of Motion • Law of action-reaction • Forces occur in pairs • The forces are equal and opposite • One force is an action force • The other force is a reaction force • The forces act on different objects