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One dimensional Motion

Motion Along a Straight Line

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Outline

• Introduction to Motion• Position Distance and Displacement• Speed and Velocity• Acceleration• Motion with constant acceleration• Free-Fall Accerelation

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Introduction to Motion

Motion is a change of position of one body with respect to another body, frame of reference, or a coordinate system.

Restriction of this lecture

1. The motion is along a straight line only2. Forces that causes motion, will not be discussed.3. The moving object is either a particle or particle -like

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Intro. cont....

Classification of Motion

1. Kinematics kinematics does not takes into account the mass of an object and force

(Consequently, NO momentum, Work or Power to be discussed.

1. Kinetics Does

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Intro. cont....

Kinematics related Parameters

 Parameter Symbol Units Position or Displacement x m Speed or Velocity v m/s Acceleration a m/s2

 Time t s

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Scalar and Vector quantities

Time, Distance and speed are a scalar quantity.

Displacement, velocity and acceleration are vector quantities

Vector quantities have magnitude and direction, while scalar quantities only have magnitude.

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Position Distance and Displacement

Position is a quantity used to locate an object relative to some reference point, called origin

Displacement is a change from one position to another position

Ex. 12 XXx

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Position and Disp. cont....

Distance Displacement

1. the actual path between two points. the shortest path between two points

2. scalar vector

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Example

100m

400m

D

CB

AIn the diagram above, there are two paths from A to D. The direct path is 400 m due East from A to D and is the displacement (and the distance) of AD. The other path, which goes from A to B to C to D, is 600 m and is the distance of that particular path. However, the displacement of the second path is still 400 m due East.  

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Speed and VelocityNotation

iX is the ith position relative to the origin

X is a displacement , X2 – X1

t Time interval, t2 –t1

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aveSt

ceDisTotalSpeedAverage

tan

avevtxvelocityAverage

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Instantaneous speed and velocity

dtdx

tx

tv

0lim

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Acceleration

aveatvonacceleratiAverage

dtdv

tv

ta

0lim

Instantaneous acceleration

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Constant acceleration

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Equation of motion with Constant Acceleration

v = v0 + at

x-x0 = v t + ½ at2

v2= v20 + 2a(x – x)

x – x0 = ½ (v0 + v)t

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Free FAll

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Example

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Example

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Example

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References

• http://www.learn.com• CD Physics version 2.0, Halliday, Resnick,

Walker and Christman, John Wiley & Sons, Inc