physics

stopping distance = thinking distance + breaking distance

• thinking distance = distance traveled by vehicle while driver reacts
• breaking distance = distance traveled by vehicle breaks bring it to a stop
• stopping distance = sum of thinking distance and breaking distance

changing stopping distance = reaction time slowed down by

• being tired
• illness
• taken drugs
• drinking alchol

• helium atoms
• contain protons, two neutrons, just like nucleas of helium atom
• have no electrons
• charge of +2
• emitted from the nucleus at high speeds
• very dangerouse

• electrons emitted from unstable nucleus
• less ionising that alpha particles (they can penetrate further)
• can be bloced by a few milimeters of alaminium or thin pieces of lead

• most penetrating, more ionising
• very high frequency emitted by electromagnetic waves
• do not have charge
• travel at speen of light
• 10x less ionising
• absorbed by many meters of concrete

• decays = whenever a piece of radioactive material gives out radioactive particles
• more it decays, more stable the material becomes
• half life = time taken for half th unstable nuclei in a sample of radioactive isotopes to decay
• geiger muller tube = number of clicks per second/minute

amount of energy transfered (Joules, J)

work done equal to energey transfered

work done = force x distance moved in direction of force

J                =   N    X   M

power = rate of doing work

measured in watts (W)

power = work done (Joules, J)

              time taken (seconds)

• velocity = speed in a given direction
• acceleration = the change in velocity per second

acceleration = change in velocity (m/s)

                       time taken (seconds, S)

A= ( V - U )

         T

• scalar - size quantity
• vector - has size and direction

speed (M/S) = distace traveled (meter, m)

                          time taken (seconds, s)

• A= acceleration
• V= final velocity
• U= starting velocity
• T= time

horrizontal line = step slope and is at a steady speed, it is accelerating

flat (stationary) line = constant speed

line going down is decelerating

acceleration = speed increasing

speed = distance

                  time                           (dont squash turtles magic triangle)

• must be a force to make any stationary object move (object will accelerate)
• balanced forces = stays the same at constant speed
• gravity pulling down
• upthrust pushing up
• force = anything that causes an object to move or change direction
• free body diagram = showing all forces, size and direction of forces

(resultant force = over all force)

force       =         mass (Kg)      x        acceleration (m/s)2

F            =                M             X                   A

(FMA magic triangle)