physics

• vector quantities have magnitude and direction
• vector quantities : force velocity displacement acceleration momentum
• scalar quantities only have magnitude and no direction
• scalar quantities : speed distance mass temperature time
• vectors are represented by an arrow, the length of the arrow shows the magnitude and the direction of the arrow shows the the direction of the quantity
• a force is a push or a pull on an object that is caused by it interacting with something
• all forces are either contact or non contact
• when two objects have to be touching for a force to act that force is called a contact force e.g. friction air resistance tension in ropes
• if the object do not need to be touching for the force to act the force is a non-contact force e.g. magnetic force gravitational force electrostatic force
• gravitational force is the force of attraction between masses
• gravity attracts all masses. on the surface of a planet it makes all things fall towards the ground and gives everything a weight
• mass is the amount of stuff in an object for any given object this wil have the same value anywhere in the universe
• weight is the force acting on an object due to gravity
• mass and weight are directly proportional
• for earth gravity = 9.8 n/kg
• a resultant force is the overall force on a point or object
• if a resultant force moves an object work is done
• to make an object move a force must be applied. the thing applying the force needs a source of energy. the force does work to move the object and energy is transferred from one stone to another
• an object is in equilibrium if the forces on it are balanced
• strecthign compressing or bending transfers energy
• when you apply a force to an object you may cause it to stretch, compress or bend. to do this you need more than one force acting on the object. an object has been elastically deformed if it can go back to its original shape and length after the force has been removed
• extension is directly proportional to force
• distance is how far an object has moved. it is a scalar quantity
• displacement is a vector quantity. it measures the distance and direction in a straight line from an objects starting point to its finishing point
• speed and velocity are both how fast you are going
• speed is just how fast you aree going
• velocity is speed in a given direction
• a person walking 1.5 m/s
• a person running 3 m/s
• a person cycling 6 m/s
• a car 25 m/s
• a train 30 m/s
• a plane 250 m/s
• uniform acceleration is speeding up or slowing down at a constant rate
• friction is always there to slow things down
• if an object has nor force propelling it along it will always slow down and stop because of friction . friction always acts in the opposite direction to movement. to travel at a steady speed the driving force needs to balance the frictional forces. you get friction between two surfaces in contact or when an object passes though a liquid. you can reduce friction between surfaces by using a lubricant
• drag increases as speed increase
• terminal velocity = maximum speed
• newtons first law : if the resultant force on a stationary object is zero the object will remain stationary. if the resultant force on a moving object is zero it will just carry on moving at the same velocity
• newtons 2nd law : the larger the resultant force acting on an the more the object accelerates the force and the acceleration are directly proportional. acceleration is also inversely proportional to the mass of the object so an object with a larger mass will accelerate less that one with a smaller mass. resultant force = mass x acceleration