radioactivity 1

• why are students values different from the expected value and how to improve the experiment

  • they are different due to the student value being significant, to improve use a light gate or drop from a taller height
• the skater is moving forward but when they throw the ball they move backwards,why is this

  • conservation of momentum
  • ball has forward momentum
  • person has backwards so total force remains the same
• the skaters wear knee pads which compress easily how do pads protect their knees when they crash on ice

  force = change in momentum/ time

  knee pads increase time of impact leading to less momentum
• a man misses shoots a bullet and hits a table rather than the cans on the table.Using inertia mass explain why the table accleration is slower

  • accleration inversely proportional to inertia mass and table has a bigger mass
• How are seismometers used to detect earth quakes

  • detection of p and s waves
  • measure the different times of arrival
  • calculate the distance from destination
• How are earthquakes produced

  • by technoic plates going over each other
• How can a teacher show how far beta particles travel in the air

  • take a measurement without the source
  • Place source near detector
  • Increase the distance between source and detector
  • Until reading gets to a constant value
• how are radio waves + gamma waves produced

  • radio waves - produced via free moving electrons in an altenrasting current or through electrical circuits.Produced intentionally .
  • Gamma rays are produced via changes in a unstable nucleus to counteract changes and make the nucleus more stable.They can be produced via pet scans or nuclear power
• dangers of radioactivity and protective measures

  • dangers - ionising,mutate cells and lead to cancer and kill cells
  • protective measures - lead sources,thongs,gloves,distance
• describe how a teacher should use a guiger muller tube to compare the count rates of two radioactive rocks

  • rocks near tube
  • measure the count rates of each tube individually
  • same time period
  • same distance
  • repeat and take averages
• What effect does alpha and beta particles have on the nucleus and describe what they are

  Alpha - positive,4 particles and not a wave helium nucleus ,mass number by 4 atomic by 2

  beta - negative,1 particle and not a wave,mass number stays the same but atomic number goes up by 1
• when white light crosses the boundary between air and glass it can split into colours of the spectrum ,why.

  white light absorbs absorbs all the colours of light,each colour has a different wavelength meaning they have different wave speed so they refract by different amount
• What is the does the curve of the graph tell u about colours and why

  curve p is silber and curve q is black because black is a better emitter of light

  
• How can a student use a semi curved block to measure the angle of incidence and the angle of refraction

  • light shown into block using a ray box
  • change the angle of incidence until the angle of refraction is 90 degrees (this is the critical angle)
  • measure angle of incidence when angle of refraction is 90
  • repeat critical angle measurements to ensure acuracy
• why does the earth not increase in temperature despite absorbing energy from the sun

  • earth radiates energy as well
  • as much energy as it absorbs
  • at the same time
• what is s-p time

  the time difference between s and p waves arriving at a certain place
• How does the change in temperature causes tectonic plates to move

  materials under the plate move sideways due to uneven heating
• state two things about the solar system that has changed over time

  • pluto is no longer a planet
  • planets orbiting the sun
  • the sun is now at the center of our planet
  • orbits are elliptical
  • planets have moons
• how does mass of a trolly effect the maximum vertical height reafhed of the trolly design an investigation

  • measure mass of trolly
  • measure the height of h with a meter rule
  • repeat for loads of masses
• what is the processes need for a nebula to undergo nuclear fusion and become a new star

  • the nebula collapses due to gravity and gravitional potential energy is converted into kinetic energy
• how does the big bang theory suggest that the universe is expanding and began at a single point

  • red shift - light for distant galaxies shifting to the red side of em waves so the observed wavelength is bigger
  • source moving away from the galaxies (Doppler effect) at an increasing rate
  • beginning at a single point - cmbr which is radiation left at the beginning
• uses of radioactive substances

  • sterlisation
  • smoke alarms
  • medicine
  • irradation of food
• why are student values greater than expected

  • different reaction times
  • students greatly exaggerated the value
• How can u examine the force on a trollly using a crumple zone and a spring or some divider on the trolly


  1. force = change in momentum / time
  2. measure the mass and time needed
  3. repeat without the spring and withy the spring and notice the difference in time for the crumple zone.the spring increases the time for the momentum to be lost by acting as a crumple zone exerting a lower force .
  4. same height when started and release without pushing
• how do newtons first law and the principle of momentum relate with each other

  • force = mass x accleration
  • change in momentum / time
  • if time of collision of two objects are trhe same the momentum is the same for both
  • forces expert and equal and opposite force
• what governs the colour of an opaque object

  • different objects reflect different waveklengths y different amounts
  • wavelengths reflected the most determine the colour
  • wavelengths that arent reflected are absorbed|
• how does heaaring work

  • sound waves travel along the ear canal and vibrate ear drums
  • vibrations are transmitted through the oacillies through ear canal and into the cochlea
  • sound is converted into electrical signals via the auditary nerve
• what is a convex lense used for

  • to treat hyperobia
• describe tir

  • only happens when the incident angle is greater than the critical angle
  • angle of incidence refraction
  • more dense to less dense
  • stays inside
• speed of ultra sound using microphones

  
  

  • use osciliscopes to see detected waves of each microscope and move microphones away until they are aligned (one wavelength)
  • measure the length the one wavelength
  • speed = frequency x wavelength
• use of infrasound

  studying the earth structure
• why are there limits to what the human ear can hear

  brain can not interpret high low frequencies

  the size of the parts in the inner ear
• refraction

  • the change of a speed of a wave
  • less dense to more dense = angle of incidence > angle of refraction slows down and bends towards normal
  • more dense to less dense angle of refraction > angle of incidence speeds up and bends away from the normal
• How does the red shift proof big bang

  • universe constantly expanding
  • with galaxies moving away from each other
• ultra sound in industrial imaging

  • flaws in objects such as pipes
  • usually reflected by far side of material
  • if there is a crack inside the object then it will be reflected back