Flashcards
Further Mechanics (5-8)
Cards in this deck (38)
- 1What is Simple Harmonic Motion?SMH is an oscillation where the acceleration is directly proportional to it's diaplacement from the equilibrium and is directed towards the equilibrium.
- 2What does the size of the restoring force depend on?The size of the restoring force depends on the displacement.
- 3What does a graph of displacement against time look like?Displacement varies as a cosine or sine wave, with a maximum value A (amplitude).
- 4What does a graph of velocity against time look like?This is the gradient of the displacement-time graph. It has a maximum value of (2pif)^2
- 5What does an acceleration against time graph look like?It is the gradient of the velocity-time graph. It has a maximum value of (2piF)^2A
- 6What is phase difference?Phase difference is how much one wave lags behind another.
- 7What id the frequency of the SHM?The frequency of the SHM is the number of cycles per second.
- 8What is the Time Period, T, of the SHM?The time period is the time taken for a complete cycle.
- 9What is the amplitude of an oscillation?The amplitude is the maximum value of the displacement.
- 10What does a graph displaying an objects kinetic energy and its potential energy when oscillating with SHM look like?
- 11How can you work out the displacement of a ball travelling in a circle attached to some string?displacement= the horizontal component so x=rcos#
- 12What is the radius of a ball being swung on some string equal to?The amplitude of the ball's SHM.
- 13Why is there a minus symbol in the equation a=-(2πft)?Because the acceleration is always acting towards the centre of the circle.
- 14Give two examples of a Simple Harmonic Oscillator.A mass on a spring
A pedulum - 15What is the size and direction of the restoring force given by?F=-kx Hookes Law
- 16How can you investigate the mass-spring system?Attach a trolley between two springs, pull it to one side by a certain amount and then let go. The trolley will oscillate back and forth. The time period, T, can be measured by getting a computer to plot a displacement-time graph. Then change either the mass or the spring stiffness and repeat.
- 17How does changing the mass of the trolley affect they time period?T² is directly proportional to m.
- 18What is the relationship between the time period and the spring constant?T² is directly proportional to 1/k.
- 19For a pendulum what is the relationship between the length of the pendulum and the time period?T² is directly proportional to L.
- 20What is the relationship between the mass and the time period?There is no relationship as T is independent of the mass of the bob, m.
- 21What is the relationship between the amplitude of the oscillation and the time period?Again there is no relationship as T is independent of A.
- 22What are free vibrations?Free vibrations are when no energy is transferred to or from the surroundings. the object will therefore oscillate at it's natural frequency.
- 23What are forced vibrations?Forced vibrations happen when there is an external driving force. The frequency of this force is called the driving frequency. If this frequency is much less than the natural frequency the two are in phase. if the df if much larger than the nf they will be out of phase.
- 24When is an object in resonance?When the driving frequency equals the objects natural frequency.
- 25What happens when an object is resonating?It gains more and more energy and so vibrates with an increasing amplitude.
- 26When in resonance what is the phase difference between the driver and oscillator?90degrees.
- 27What are some examples of resonance?- A Radio tuned at the same frequency as the radio station
- A glass resonating when driven by a sound wave at the right frequency
-Organ pipe
-A swing - 28What are damping forces?Frictional forces such as air resistance.
- 29What is light damping?When the system takes a long time to stop oscillating.
- 30What does a graph showing light damping look like?
- 31What is heavy damping?Heavy damping means that the systems takes a much shorter time to stop oscillating and it's amplitude gets much smaller each period.
- 32What does a graph showing heavy damping look like?
- 33What is critical damping?
- 34What does a graph showing critical damping look like?
- 35What is overdamping?Overdamping is when it takes longer to return to the equilibrium than a critically damped system.
- 36What does a graph showing overdamping look like?
- 37What do the resonance peaks for the different damping methods look like?
- 38How can you demonstrate the effect od damping on a spring-mass system?A flat disc is attached to two springs (one under it and one above it). A mass is placed on this disc. As the mass oscillates, air resistance on the disc acts as a damping force, reducing the amplitude of oscillation. The larger the disc the larger the damping force.