# Physics

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• Created by: Ashleigh
• Created on: 30-11-12 18:31
• Physics
• Resultant Force
• An object has many different forces adding upon it.
• These can be added up into a single force: the resultant force.
• When all the forces are balanced, the resultant force is zero.
• A stationary object remains stationary.
• Moving objects keep moving at the same pace and in the same direction.
• When all the forces are not balanced, the resultant force is not zero
• In this case the object accelerates in the direction of the resultant force.
• A stationary object begins to move in the direction of the resultant force.
• A moving object will speed up, slow down or change direction depending on the resultant force.
• Force, Mass and Acceleration.
• Size of force: Obejcts accelerate in the direction of resultant force
• Bigger the resultant force the bigger the acceleration.
• Doubling the size of the resultant force doubles the acceleration.
• Mass: A force on a large mass will accelerate it less than the same force on a smaller mass.
• Size of force: Obejcts accelerate in the direction of resultant force
• Bigger the resultant force the bigger the acceleration.
• Doubling the size of the resultant force doubles the acceleration.
• Doubling the mass halves the acceleration.
• Calculating Acceleration: A = F/M
• F = Resultant Force, Newtons (N)
• A = Acceleration of the object, Metres per seconds (M/Ssquare)
• M = Mass, Kilograms (KG)
• Forces and motion
• Distance-time graphs
• Vertical axis = distance
• Horizontal axis = time
• When an object is stationary, the line on the graph is horizontal
• When an object is moving at a steady in a straight line, the line on the graph is also straight but sloped.
• Steeper the line the greater the speed of the object.
• Calcuating speed
• Speed (m/s) = Distance travelled (m) / Time taken (s)
• Velocity-time graphs
• The velocity of an object is it's speed in a particular direction
• Two different cars will have different velocities if they are travelling at:
• The same speed but in different directions.
• The different speeds in the same direction
• different speeds in different directions
• different speeds in different directions
• Vertical axis = Velocity of the object
• Horizontal axis = time
• when an object is moving with a constant velocity, the line on the graph is horizontal
• when an object is moving with a constant acceleration, the line is straight but steep
• The steeper the line, the greater the acceleration.
• a line sloping downwards - with a negative gradient - represents an object with a constant deceleration (slowing down)
• Do not confuse
• Distance-time graphs
• Vertical axis = distance
• Horizontal axis = time
• When an object is stationary, the line on the graph is horizontal
• When an object is moving at a steady in a straight line, the line on the graph is also straight but sloped.
• Steeper the line the greater the speed of the object.
• Acceleration
• A = (u-v) / T
• A = Acceleration (m/ssquare)
• u = final velocity (m/s)
• v = starting velocity (m/s)
• T = time taken (s)
• Moving objects keep moving at the same pace and in the same direction.
• You can not possiblity tell which is correct unless you know if the object is moving or not.
• A moving object will speed up, slow down or change direction depending on the resultant force.
• A stationary object begins to move in the direction of the resultant force.
• A stationary object remains stationary.
• To calcuate the gradient of the line divide the change in the vertical axis by the change in the horizontal axis