Physics Flashcards
How is sound made
Sound is made by vibrations or oscillations
Name some sources of vibrations
Some sources of vibrations are vocal chords, strings/instruments, trumpets (lips), oboe (reed)
What part of the ear vibrates?
Our eardrum vibrates
How does sound travel from a source to our ears?
Sound travels in compressions and rarefactions (longitudinal waves) which’s vibrates the air particles which travel to the ear and vibrate ear drum
Describe a experiement that shows sound travels in longitudinal waves
You turn a loudspeaker on at low frequency (vibrates few time per second) so you can easily see done vibrate though you will hear no sound. The candle flame should flicker left to right meaning it vibrate at the same direction the sound flows.
What caused the candle to do this?
The loudspeaker caused the air next to it to vibrate left & right , this eventually caused the air next to the flame to vibrate left and right. This vibrating air pushed and pulled on the flame itself
Describe the slinky demonstrations and why we use it
We use the slinky demonstration to show the compressions and rarefactions of a longitudinal wave on a slinky. The hand vibrates/ pushed and pulled on the slinky left and right. The compressions travelled to the right and the coils vibrated left to right in order to pass the vibration
Describe the bell jar demonstration and it’s aim
The bell jar demonstration aim is to find out wether sound can travel through a vacuum. When the glass chamber has air in it you can hear a sound. As the air particles got removed from the chamber the sound got quieter and when the air was completely removed there was no sound. This proves that there is no sound in space (can not hear you scream)
How do you measure the speed of sound
Measure with the trundle wheel a suitably large distance. The timer starts when you see two blocks of wood being hit together (or a gun being shot) , once you hear the sound stop the timer. Repeat two times. Do the speed equation to find out
What does Mach 1 mean?
Mach 1 one means the speed of sound (300 m per second)
What happens when Mach 1 is exceeded
When Mach 1 is exceeded the sound barrier is broken (sonic boom)
How do you create a audible echo?
You create a audible echo by having sound reflect off of something
How do you measure the speed of sound using echoes
D=s t/2
Name a use of echoes
You can use each ones to echolocate objects, some animals that use echolocation are bats, dolphins etc
What is reverberation
Reverberation is a echo which reverberates back to the original source
What does frequency mean
Frequency is the pitch, high pitch is a high frequency and a low frequency is low pitched (longer wave length)
What does amplitude mean
Amplitude means the loudness
How is frequency related to the pitch?
The higher the frequency the higher the pitch (and reversed)
What does a frequency of 1MHz mean
A frequency of 1MHz means 1000000 vibrations per second
What does a frequency of 1kHz mean
A frequency of 1kHz means 1000 vibrations per second
What is a sonar
A sonar is a ping (very short pulse of sound) is sent by a boat towards the sea floor. Etc
What is the force of gravity
The force of gravity is weight
What is the force between two opposite magnetic poles
the force between two opposite magnetic poles is attraction (north+south)
What is the force in a squashed stress ball
the force in a squashed stress ball is compression
What is the force on a aircraft wing
The force on a aircraft wing is lift
What is the force caused by liquids and gases that opposes the motion of bodies that move through them
the force caused by liquids and gases that opposes the motion of bodies that move through them is drag (air resistance)
What is the force between two like magnetic poles
the force between two like magnetic poles is repulsion (north and north, south and south)
What is the force in a stretched spring
the force in a stretched spring is tension
What is the force between two surfaces that oppose motion
the force between two surfaces that oppose motion is friction
What is the force of a engine
the force of a engine is thrust
What is the unit for force
The unit for force is Newton’s
What effect do balanced forces have on a stationary body?
If the forces are balanced they will have no effect on the body, it will stay stationary
What effects do balanced forces have on a moving body?
If the forces are balanced there will be no effect and the body will continue moving
What does resultant force mean.
Resultant force is if the forces are opposite (right, left) they will be taken away. If the forces are on the same side they are added
What effect does a resultant force have on a stationary body
The resultant force will move the body in its direction
What effect will the resultant force have on a moving body
The resultant force will continue moving the body in its direction
What causes friction?
Friction is caused when surfaces are in contact which are either moving over each other or attempting to do so
Name some examples of friction being useful
Some examples of friction being useful are trainors (without you will slip), sander (friction gets rid of bumpy bits), Matches (need friction to start fire/generate heat)
Name some examples of friction being a nuisance
Some examples of friction being a nuisance are skiiing (slows you down), biking (slows down speed), gears (2 surfaces moving over each other will ware it away)
State the factors affecting static friction
The factors affecting static friction are the heavier it is the more static friction, the lighter it is the less static friction
What are the four factors affecting drag?
The four factors affecting drag are area, speed, viscosity, shape
What are the 5 forces that change the shape of materials
the 5 forces that change the shape of materials are compression, tension, bending, torsion, shear
What is the relationship between the tension force in a spring and it’s extension
the relationship between the tension force in a spring and it’s extension is the more force the more extension and the less force the less extension
What are the names of the magnetic materials
the names of the magnetic materials are iron, cobalt, nickel, steel, neodymium, lodestones, godolinium, dysprosium, samarian
What two metals are not magnetic
Copper and aluminium are not magnetic
What are the types of poles
The poles are north and south
What is the different between a magnet and a magnetic material
A magnet is a magnetic material with poles and a magnetic material is a magnetic material with no poles
What do all magnets have
All magnets have 2 poles
Where is magnetism strongest at?
Magnetism is strongest at the poles
What are the laws of magnetism
The laws of magnetism are magnets can exert forces on other magnets, magnets exert forces on other unmagnetised magnetic materials, like poles repel, opposite poles attract, both poles will always attract unmagnetised materials
How do you induce poles
You induce poles by bringing a piece of unmagnetised magnetic material and touches or is brought near to the pole of a permanent magnet, it becomes a magnet itself. The magnetism is induced.
What is the test for magnetism
The test for magnetism is take a bae magnet and bring each North Pole close to the end of the rod. See wether it attracts or repels, if it attracts it is a magnet
How do forces vary
Forces vary with distance from poles
How do you investigate the variation of force with distance from poles
you investigate the variation of force with distance from poles by placing a compass on points, and draw a dot at the other end of the arrow and move the compass so that it points directly towards or away from the drawn dot. Repeat this until either the dots go off the sheet or curve back into the magnet. Join the dots with a smooth curve and repeat until a symmetrical pattern is seen
What is a magnetic field
A magnetic field is a the space around a magnet where forces are felt
How does a compass work
A compass is a bar magnet that is free to spin so that it lines up with magnetic fields
How do you make a compass?
To make a compass you place a bar magnet on two watch glasses. The magnet should spin to the right direction.
Does the earth have a magnetic field
Yes the earth does have a magnetic field
How is the earths magnetic field created?
the earths magnetic field is created by electric currents which conduct from its core. The earths magnetic north changes everyday due to the the liquid metal surrounding the inner core whereas the true north doesn’t move
Which way does a compass point?
A compass points to the true north
How do you make permanent magnets?
You make a permanent magnet by taking a steel optical pin and tape it to the lab bench. Take a bar magnet and stroke the pin with the north end of a bar magnet many times ensuring you use a wide arc.
Check poles by placing a compass near each pin ensuring you use a working compass and blueback the needle to a cork and float it in water. Detach the pin from cork and cut pin in half with wire cutters, use a compass to test wether there are any poles where the pin was cut in two
What is hard magnetism and give a example
Hard magnets also referred to as permanent magnets, are magnetic materials that retain their magnetism after being magnetised. A example is iron
What is soft magnetism and give a example
Soft magnets are materials that are easily magnetised and demagnetised a example is aluminium
