10A.4

Question 1

what is free oscillation

Answer 1

the oscillation of a system, free from the influence of any forces from outside the system

Question 2

what is natural frequency

Answer 2

the frequency of oscillation a system will take if it undergoes free oscillation

Question 3

a free oscillation system

Answer 3

allows for a constant exchange of potential and kinetic energy

Question 4

the exchange of energy in oscillation is caused by

Answer 4

a restoring force which is proportional to the displacement

Question 5

what is forced oscillation

Answer 5

the oscillation of a system under the influence of an external (usually repeatedly applied) force

Question 6

what is driving frequency

Answer 6

the frequency of an external force applied to the system undergoing forced oscillations

Question 7

if you are forcing oscillations you are

Answer 7

adding energy to the system

Question 8

when you add energy to the system in forced oscillations and that’s not done at the natural frequency it wont undergo

Answer 8

SHM and will dissipate energy quite quickly

Question 9

what is resonance

Answer 9

very large amplitude oscillation that occurs once the driving frequency matched the natural frequency

Question 10

when a system is forced to oscillate at its natural frequency it will

Answer 10

absorb more and more enegry

Question 11

how can we investigate the resonant frequency

Answer 11

get a spring attach a hanging mass onto it, then attach a vibrations generator with a signal generator to the spring making the spring vibrate to different frequencies with all of the set up being held by a clamp and stand, then with the use of a motion sensor and a computer datalog find the different heights of mass at different frequencies(i.e monitor the amp of vibrations) until you find the max amplitude, the f at that amplitude will be the resonant frequency

Question 12

after finding out the resonant frequency how may we find the mass of the hanging object, or the (springs) constant

Answer 12

by using the fact that t = 1/ f and with that f = 1/2pi√ k/m and rearrange to find m and k respectfully

Question 13

what is a safety precaution we should take when investigating resonance

Answer 13

1. use a stand clamped to the bench to hold the vibration generator
2. use small mass and keep the vibrations small

Question 14

what will happen to a pendulum amp if its left to swing

Answer 14

it will constantly decrease with each swing due to air resistance and the internal stresses within the flexing material of the string

Question 15

what are damped oscillations

Answer 15

it is when work is on the damping system, and energy is dissipated in the damping system with each oscillation, so the amplitude of oscillation decreases

Question 16

what is damping

Answer 16

a material, or system, causing energy loss during each damped collision for example attaching a small sail onto a pendulum so the air résistance can have a greater affect

Question 17

what is underdamping

Answer 17

when the amplitude decreases exponentially and the oscillator completes several oscillations before stopping

Question 18

what is overdamping

Answer 18

when the amplitude of oscillation drops very rapidly where it might not even complete one cycle (example: having the pendulum swing through a bowl of water)

Question 19

what is critical damping

Answer 19

when damping is such that the oscillator would return to its eq position in the quickest possible time, without going past that position

Question 20

what does a displacement against time graph look like for all types of damping (critical damping, underdamping, over damping, undamped)

Answer 20

page 161

Question 21

how can we investigate damping

Answer 21

setting up a spring with hanging masses system held by stamp and clamed to the table, and with a motion senor with a computer datalog to measure the amp of vibrations, so after setting that up get a card sail that will act as an air resistance (it increases it). altering the size of the card would change the damping effect making the amp change and decrease more

Question 22

what is a safety precaution when investigating damping

Answer 22

1. make sure the spring is held securely in the clamp

2, only hang small mases

Question 23

What can over damping be used in

Answer 23

car suspension systems, but too much overdamping could cause the oscillator to take a very long time to return to its original eq position

Question 24

what is the solution for noise or problems that can be caused from a oscillator at its natural frequency

Answer 24

the solution is using a damping system whish differs from oscillator to oscillator

Question 25

what is the best damping system called and its description and examples of it

Answer 25

the critical damping system (so that the system returns to its original eq position) which is specific for each use for example a clock needs to have a longer critical damping, while the bike needs to have a short one (i think so check with the sir)

Question 26

how can we investigate damping solutions to design problems

Answer 26

by setting up a signal generator connected to a vibration generator to produce DRIVING FORCES (imp key word) with changeable frequency, and then using this to set up a model of an earthquake shaking a building and seeing how dampers could be attached to the model, internally or externally to reduce the damage caused by resonance

Question 27

why should a climbing rope be both stretchy and stiff

Answer 27

it needs to be stretchy so that to avoid sudden painful stop, but stiff to bring the climber to a safe halt without hitting the ground

Question 28

why does a climbing rope after the fall need to be plastically deformed

Answer 28

since the material is ductile the plastic deformation would reduce the amp of oscillation and it will provide critical damping, any less stiff material wont have enoughdamping to reduce the oscillations safely

Question 29

during earthquakes steel framed building can

Answer 29

absorb the vibration energy since steal is ductile so its plastic deformation damps the oscillations