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9 Motion Alonga Straight Line
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9 Motion along a Straight Line
Should this topic betaught after Chapter
3 ( Integrat ion).....?
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Untuk renungan bersama
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9 Motion along a Straight Line
CANDIDATES should know the basicsfirst .....
basic differentiation
basic integration
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Hence its advisable that students are evaluated
on these skills before the actual lesson starts...
(use different letters not just y and x)
eg. y = 2x3 , y = x24x + 3, v = 2t(3 t)
s = t36t2 + 3t 1 , a = 10 2t
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s = displacement(distancemeasured from a certain point +direction)
v = velocityof moving object[usually towards the right is
consideredpositive]a = accelerationof moving object
9 Motion along a Straight LineF5
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[Differentiation]
s
v
a
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,
ds
v dt
2
2
dv d s
a dt dt
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[Integration]
a v s
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,
s vdt dv
a dtdt
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9 Motion along a Straight Line
PAST YEAR QUESTIONS ......(2003) a = 10 2t
(2004) v = 2t ( 6 t)
(2005) (Involves two moving objects, P & Q)vP = 6 + 4t 2t2 (ms-1)
vQ = 2 ms-1
(2006) v = t2
6t + 5(2007) v = t26t + 8
(2008) v = 10 + 3t t2
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Why almost all v s . ??
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9 Motion along a Straight Line : KEY WORDS 1
Initialdisplacement
Initialvelocity
Initialacceleration...
Initial : when t = 0(At the beginning )
t = 0, s = .....
t = 0, v = .....
t = 0, a = .....
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9 Motion along a Straight Line : KEY WORDS 2
Particle returns to
starting point O...
Particlepasses
through O again ... Particle has
maximum / minimum
velocity..
Particleachieves
maximum
displacement...
displacement, s = 0
s = 0
acceleration, a = 0
Velocity, v = 0
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9 Motion along a Straight Line : KEY WORDS 3
Particlestopsinstantaneously at C ....
Particlereverses /changesits direction ofmotion ...
Particle moves withconstant velocity...
Particles moves to theleft...
Time interval duringwhich the acceleration
ispositive
At C, v = 0
v = 0
acceleration,a = 0
Velocity, v < 0
a > 0, find range of t
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9 Motion along a Straight Line : KEY WORDS 4
Distance travelled from t = a tot = b is ........
b
a
t
t
dtV
S =Note : Must integrate v, which must be in terms of t
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9 Motion along a Straight Line : KEY WORDS 5
Distance travelled during the thirdsecond =
2
3t
t
dtV
S =Note : Must integrate v, which must be in terms of t
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9 Motion along a Straight Line :Test you r unders tand ing .....
Particle returns to startingpoint O...
Particlepasses through Oagain ...
Particle has maximum /minimum velocity..
Particleachieves maximumdisplacement...
Particle stops instantaneously
Particlereverses / changes itsdirection...
Particle moves with constantvelocity...
s = 0
s = 0 a = 0
v = 0
v = 0 v = 0
a = 0
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9 Motion along a Straight Line
(More challenging questions...)
Question involving motion of TWOparticles.
1. ... When will both of them collide / meet ??? Howdo we know both particles are of the same
direction at time t ???
2. The range of time at which the particle returns.
3. The range of time when the particle moves with
negative displacement
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(More challenging questions...)
4. The distance travelled in the nthsecond
5. Negativevelocity
6. Speed which is increasing
7. Total distance travelled..
8. Sketch the velocity-time graph for 0 t5.
