AT3

• speed is known as scalar quantity. scalars have magnitude but no direction. speed is the rate at which an object is moving ( distance an object travels over time)
• velocity is a vector quantity. they have magnitude (size) and direction. velocity - another word of speed but with direction
• distance - scalar representing total distance travelled
• displacement - vector representing change in position
• converting m/s to km/h - x 3.6 from km/h to m/s divide 3.6
• displacement time graph - gradient = rise/run = change in displacement/ change in time = speed , find the area under the graph
• distance time graphs - shows the total distance traveled since the start of the journey - never decrease, gradient = speed
• acceleration - rate of change in speed or direction of motion. happens whenever there are unbalanced forces ( net force doesnt equal to zero) units = m/s^2 or ms-2
• constant acceleration - velocity increases by the same amount per second
• deceleration - slows down
• deceleration have positive velocity but negative acceleration
• acceleration have both positive acceleration and velocity
• acceleration = speed/ time, or final velocity - initial velocity divide by time
• motion capture image involve recording the position fo a moving object at regular intervals
• force - a push or pull. - causes acceleration - measured in newtons
• contact force - object must be in contact to push or pull others
• field force - an object that exerts field force doesnt need to touch another object to exert a force on it
• friction - force that resist motion, acting between surfaces. it increases as the surface is rough or sticky or the object is pressed more on surface. Friction resist motion by converting kinetic energy to heat
• air resistance is the force that resist motion as an object travels through air. it converts kinetic energy to heat. air resistance on an object increases as the surface area/ speed increases/ travels through denser air
• buoyancy - force exerted by fluids ( liquid) surrounding an object. when the object is less dense than the fluid it has more buoyant
• normal force - force acting on an object pressing into a surface. - always perpendicular to the surface doesnt have to be vertically upwards
• tension - pulling force acting through a solid object ( string/ rope/ spring)
• gravitational force - field force, acts between object with mass. the more mass the stronger the gravitational field is
• net force is the sum of forces of an object
• balance forces means that net force equals to 0, object doesnt accelerates
• unbalanced force means net force doesnt equal to 0, object accelerates
• law of inertia - tendency of something to remain unchanged.
• mass - amount of substance in an object
• weight - same as gravitational force - calculated by newton 2nd law
• acceleration - rate of change in speed/ direction of motion - positive velocity and poxitive acceleration
• constant acceleration - velocity increase by same amount per second
• acceleration happens whenever there is unbalance force
• deceleration - slows down, still accelerates - positive velocity negative acceleration
• nucleus - controls the cell - contains most of the genetic material dna
• cytoplasm - jelly like substance - many cell reaction within
• cell membrane - allows substance to go in and out the cell
• mitochondria - produces energy needed to power the cell
• chloroplasts - green discs that allow the plant to make food by photosynthesis
• vacuole - storage space filled with cell sap
• cell wall - supports the cell