Physics Chapter 2 Notes
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Transcript of Physics Chapter 2 Notes
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Physics Chapter 2 NotesSpeed, Velocity, and Acceleration
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Displacement• The distance in a straight line in a certain direction from the
starting point• Eg Lily walked 1km to the North, then 2km to the East
followed by 1km to the south.• a. what is her total walking distance?• b. what is her final displacement?
• Answers:• a. 1 + 2 + 1 = 4km• b. 2m due east from starting point
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Speed and Velocity• Scalar: has only magnitude and no direction• Speed is distance travelled by a body per unit time
• Vector: has both magnitude and direction• Velocity is distance travelled per unit time in a stated direction
• Units: ms-1 or kmh-1
• Average speed is NOT the constant speed
• Instantaneous speed: the speed at any instant• Use speedometer to find instantaneous speed• Can be found by finding the gradient of the tangent to the
displacement-time graph, at that point in time
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Speed measurement using ticker-tape timer
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Acceleration• Defined as the rate of change of velocity with time
• Units: ms-2 or kmh-2
• If velocity is constant, acceleration= 0• If velocity decreasing negative acceleration/deceleration• The gradient of a velocity-time graph of a moving object gives
the acceleration of the object at a given time
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Acceleration of bodies falling near to earth• An object falling near to Earth, where the air resistance is
negligible, has a velocity-time graph that is s straight line. It falls with a constant acceleration
• The only force acting on the object experiencing free fall is the force of gravity
• Acceleration = 10ms-2
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Acceleration-time graphs
Decreasing acceleration Decreasing speed Constant speed
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Velocity-time graphs
Increasing acceleration Constant acceleration
Zero accelerationConstant speedConstant speed
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Distance-time graph
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Area under velocity-time graph• Area under velocity-time
graph is the distance