Section 6: Oscillations
Revision spread1 : Simple harmonic motion
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Checkpoints : （1)recall that the condition for simple harmonic motion is F=-kx
Identify situations in which simple harmonic motion will occur.
(2) recognize吝啬怎么读 and u the expressions a=—ω2x， a=-Aω2xcosωt，
v=—Aωsinωt，x=Acosωt,and T=1/f=2π/ω as applied to a simple harmonic oscillator。
(3） obtain a displacement—time graph for an oscillating object and recognize that the gradient at a point gives the velocity at that point.bdb
（201306-1）A mass is bouncing on the end of a vertical spring。 Its motion will be simple harmonic if the spring
A .can store energy. B 。has elasticity.
C .is hung vertically. D .obeys Hooke’s law。比较级和最高级的用法
（201206—4）Which of the following is not an example of simple harmonic motion？
A A car bouncing on its suspension system。
B A child jumping on a trampoline。
C A person bouncing on the end of a bungee cord。
D A swinging pendulum in a grandfather clock。
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（201201—13） (a） Define simple harmonic motion
(b） The graph shows the variation in water level displacement with time for the water in a harbour。 The water level displacement varies with simple harmonic motion。
(i) U the graph to calculate the amplitude and the time period of the variation in the water level displacement。
（ii) Show that the maximum rate of change of water level displacement is about 0。6 m hour–1
。
(iii) On the axis below sketch how the rate of change of water level displacement varies with time for the interval 0–30 hours。 The variation in water level displacement with time has been drawn for you。 You need not add any numerical values to the y-axis。
Revision spread2 ：Energy and damping in SHM
Checkpoints : (1）Recall that the total energy of an undamped SHM system remains constant and recognize ad u expressions for the total energy of an oscillator。
（2） Distinguish between free and damped oscillations
(201306r-7) An object is hung from a vertical spring and undergoes undamped simple harmonic motion. 研究生预报名是什么意思It is correct to say that there are no changes in the
A .elastic potential energy of the oscillating system。
huay B 。gravitational potential energy of the oscillating system.
C 。kinetic energy of the oscillating system。
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D .total energy of the oscillating system。
复式记帐period是什么意思（201306—9） For an object undergoing simple harmonic motion lect the graph that reprents the variation of kinetic energy with displacement.
（201306-10） For an object undergoing simple harmonic motion lect the graph that reprents the variation of the total energy with displacement.
Revision spread3 ：Forced oscillations and resonance 。
Checkpoints : （1)Distinguish between free， damped and forced oscillations .
(2) Investigate and recall how the amplitude of a forced oscillation changes at and around the natural frequency of a system .
Describe qualitatively how damping affects resonance .
(3)Explain how damping and the plastic deformation of ductile materials reduce the 儿童节快乐的英文amplitude of oscillation 。
（201306-8) A car is travelling over a rough road surface. At low speed the ride is very bumpy with the car and its occupants suffering large amplitude vertical oscillations。 However, when the car is driven at a higher speed the ride gets smoother. This is becau at the higher speed
A 。the car leaves the ground and miss the bumps.
B 。the car crushes the bumps and makes the road smoother.
