Periodic Motion Flashcards
what happens to the speed, velocity and acceleration when an object is moving in circular motion
speed is constant, it has a constant changing velocity as velocity has both magnitude and direction and it is changing direction, therefore the object is accelerating
which direction does the centripetal force act
towards the center of the circle
how do we know an object moving in circular motion must experience a force
from newtons firsts law - that to accelerate, an object must experience a resultant force, therefore an object moving in a circle must experience a force
what is the force that acts on objects in circular motion
centripetal force
what is the angular speed
the angle an object moves through per unit time
what is a radian defined as
as the angle in the sector of a circle when the arc length of that sector is equal to the radius of the circle
when does an object undergo simple harmonic motion
when its acceleration is directly proportional to displacement and is in the opposite direction
what is the amplitude equal to
max displacement
if a displacement time graph is a sin graph what would be the shape of a velocity time graph
cos graph
if a velocity time graph was a cos graph what would be the shape of an acceleration tike graph
-sin graph
what is a simple harmonic system
are those which oscillate with simple harmonic motion
what are the two examples of simple harmonic motion we need to know
a simple pendulum and a mass-spring system
what does the simple pendulum involve
a small dense bob of mass m hangs from a string of length l, which is attached to a fixed point. when the bob is displaced by a small angle (less than 10 degrees) and let it go it will oscillate with SHM
why does the angle need to be less then 10 degrees
due to the derivation of the formula as a small angle approximation is used and so for larger initial angles this approximation is no longer valid and would not be a good model
during its oscillations how is its energy transferred
its gravitational potential energy is transferred to kinetic energy and then back to gravitational potential energy and so on
what are the two types of mass spring systems and what is the difference about them
when the spring is either vertical or horizontal. the difference is the energy which is transferred during oscillations
how is the energy transferred in a vertical system
kinetic energy is converted to both elastic and gravitational potential energy
how is the energy transferred in a horizontal system
kinetic energy is transferred only to elastic potential energy
which energy is at its max when the oscillation is at its equilibrium position
the kinetic energy is at its max
what happens to the total energy of a system if there is no air resistance
it remains constant
what energy will be at its max when it is at the amplitude of its oscillations
the max amount of potential energy
if there is air resistance how is energy lost
lost as heat
what is damping
is where the energy is an oscillating is lost to the environment, leading to reduced amplitude of oscillations
what are the 3 types of damping
light, critical, heavy
what is light damping
this is also known as under-damping and this is where the amplitude gradually decreases by a small amount each oscillation
what is heavy damping
also known as over-damping and this is where the amplitude reduces slower than with critical damping, but also without any additional oscillations
what is critical damping
this reduces the amplitude to zero in the shortest possible time
when do free vibrations occur
when no external force is continuously acting on the system, therefore the system will oscillate at its natural frequency
what are forced vibrations
are where the system experiences an external driving force which causes it to oscillate, the frequency of this driving force, known as driving frequency, is significant
what occurs when the driving frequency is equal to the natural frequency of a system
resonance
what is resonance
is where the amplitude of oscillations of a system drastically increase due to gaining an increased amount of energy from the driving force
what are the 3 applications of resonance
instruments- an instrument such as a flute has a long tube in which air resonates, causing a stationary sound wave to be formed
radio - these are tuned so that their electric circuit resonates at the same frequency as the desired broadcast frequency
swing - if someone pushes you on a swing they are providing a driving frequency, which can cause resonance if its equal to the resonant frequency and cause you to swing higher
what is an example of a negative consequence of resonance
can cause damage to structure, an example is a bridge when the people crossing it are providing a driving frequency close to the natural frequency, it will begin to oscillate violently which could be very dangerous and damage the bridge
what can reduce the effects of resonance
damping
