Physics 2

Physics 2

1. Acceleration is how quickly velocity is changing

   • acceleration=change in velocity/ time taken

2. weight and mass not the same thing

   • weight = mass x gravitational field strenght
   • Mass is in kg and weight is in newtons
     • mass is the measure of how much matter an object has- weight is the measure of how strongly gravity pulls on that matter

3. forces

   • when a force moves an object through a distance energy is tranferred and work is done
     • Work Done = Force x Distance
       • Gravitational potential energy= mass x g x height
         • Power = work done (or energy transferred)/ Time taken
           • Momentum (kg m/s) = Mass(kg) x Velocity (m/s)
   • Resultant force
     • a stationary objects resultant force is zero
       • If the resultant force on a moving object is zero the object will continue to move in the same direction at the same speed
     • F= ma
       • m=mass (kg) a= acceleration (m/s) F=resultant force in newtons
   • When two object interact the forces they exert on each other are equal and opposite
   • Resistance
     • resistance- from fluid (air or liquid)
       • reduce resistance by making object streamline
       • increases as speed increases
   • Friction
     • friction - opposite direction to movement
   • Cars
     • things that affect stopping distance: speed of vehicle, thinking distance, weather
       • new car design
         • brakes - rather then converting the kinetic energy of the vechicl to heat enegry, brakes put vechiles motor into reverse- motor goes backwards wheels slow down - electric generator then stores this energy
         • Cars designed to convert kinetic energy safely in a crash
           • by increasing time over which momentum changes happen to lesson forces on passenger
           • Crumple zones
           • Air bags
           • side impact bars
     • two different parts of overall stopping distance of a car- thinking distance and braking distance
   • Terminal velocity

4. Atomic structure

   • Plum pudding
   • Isotopes- same number of protons but different number of neutrons
     • most isotopes are radioactive, which means they decay into other elements and give out radiation
   • Types of radiation
     • alpha
       • slow moving , big ,ionising
       • helium- 2 neutrons, two protons
     • beta
       • quite fast, moderately ionising, simply an electron- charge of -1
     • gamma
       • penetrate far into materials, no mass or charge , weakly ionising

5. Electricity

   • Static electricity
     • caused by friction
       • insultating materials
         • result of a imbalance between positve and negative charges in an object. Build up on surface of a object and find a way to be released
           • rubbing certain materials against one another can transfer negative charges, or electons
           • only electons move- negative charges!
     • opposites repel
       • Charges attract
   • current- flow of electricity
     • Resistnace- anything in circuit which slows the flow down
       • resistance increases with temperature
         • due to some electical energy transferred to heat energy
   • ammeter measures current
     • voltmeter measure potential differnce
   • types of circuits
     • series-
       • All of nothing
     • parellel
       • independance and isolation

6. Difference in speed and velocity - velocity involves speed and idrection

Bilder und Dateien der Mindmap