Exams-Science 8 Flashcards
(45 cards)
Dependent variable
the effect on a experiment
Fluid
can change shape w/o separating
Controlled variable
all other factors that can influence an experiment
pressure
the amount of force upon an area
independent variable
an experimenter purposely changes this to determine its effect or outcome
Describe how mass, inertia, and friction are related?
The more mass, the more inertia, therefore the more friction needed to slow a stop
Define terminal velocity
terminal velocity’s rate of acceleration is 0 meters per second squared. Terminal velocity is the highest speed that a falling object can achieve. The forces of air resistance and gravity must be equal. The more mass, the more speed revealed
The Kinetic Theory of matter
The kinetic theory of matter states that particles, atoms, molecule; basically all matter is moving. Due to the enormous amount of space between particles.
Solid
movement of particles is the slowest, has a definite shape, particles typically vibrate back and forth in place, strongest force of attraction between particles, cannot be compressed
Gas
particles are usually the farthest apart form one another, easily compressed, takes the shape of its container, weakest force of attraction between particles
Liquid
takes the shape of its container, can be compressed but difficult to do so, particles move at “medium speed”, particles are of “medium” distance between each other
IKE
internal kinetic energy-molecules that are inside the moving objects in motion (molecules moving) Ex: water that is moving
EKE
external kinetic energy- motion you can visually see Ex: motions of a car
IPE
internal potential energy- changing the distance btween molecules
EPE
external potential energy-movement about to occur, that can be seen. Ex: rock being lifted and held above the earths surface.
What occurs to temperature (speed of particles) and the distance between particles during a phase change
during a phase change speed doesn’t change. Heat is still being lost or gained but temperature stays the same. The distance between molecules increases (solids or liquids) or decreases (liquid to solid)
Why does evaporation cause cooling on a molecular level
when heat is great enough, bonds break and molecules change into a gas. As a result, the heat is taken away leaving the surface cooler. The weaker the bonds, the easier they are broken, the faster the evaporation, the cooler the surface.
The conservation of matter
matter is never created or destroyed, only converted. Therefore, the amount of matter does not increase or decrease, but changes either physically or chemically
Physical change
A physical change is any observable characteristic without changing the substance itself. (color, size, shape, phase). A chemical change is one or more substances in a material into a different substance. (A physical change also occurs).
Melting Iron
Physical
Burning Magnesium
Chemical Change
opening a can of soda
physical
salt and water
physical + chemical
sodium and water
chemical change
