Download Science 7ACC Midterm Review

Science 7ACC Midterm Review
YOU SHOULD KNOW…
Scientific Method and Metric Measurement
 The metric system is based on multiples of 10.
 How to do metric conversions (Ex: 64 cm = 0.00064 km)
 The appropriate units of measurements: liquid volume = liter, mass = gram, length =
meter, temperature = Celsius.
 How to measure using a metric ruler.
 How to calculate the volume of a rectangular shaped object: v = length x width x height.
o That the unit of volume is cm3. For water, 1 cm3 = 1 ml.
 How to determine the volume of an irregularly shaped object using volume displacement.
o Ex: The volume of water in a graduated cylinder increased from 20 to 50 ml when a
rock was dropped down. The volume of the rock is 30 ml.
 How to calculate volume and mass and determine density using the formula: d = m/v
o That the unit of density is g/cm3 and that the density of water is 1 g/cm3.
o That an object with a density greater than water will sink; an object with a density
less than water will float.
 The Scientific Method is a process used to solve problems and answer questions.
o A hypothesis is an educated guess or testable prediction.
o A variable is something that can be changed and a control is used as a comparison.
o An independent variable can be changed by the person doing the experiment and
affects the dependent variable.
o Charts, graphs, and tables should be used when analyzing data.
Matter
 Examples of physical properties of matter such as malleability, ductility and conductivity,
and be able to explain what they mean.
 The properties of the states of matter:
o Solid- definite shape and volume, Liquid- definite volume only, Gas- no definite
volume or shape.
 Physical changes do not produce new substances but chemical changes do.
 The states/phases of matter are physical changes:
MELTING
EVAPORATION
SOLID
LIQUID
GAS
FREEZING
CONDENSATION
SUBLIMATION
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o Adding or removing heat affects the speed of the particles and the state of matter.
Mixtures are physically combined.
Dissolved particles that become very small but keep their identity.
The signs of a chemical change include release of heat, light, electricity, bubbles and the
formation of a new substance.
Energy
 Energy is defined as the ability to do work and is measured in joules.
 Law of conservation of energy states that energy is neither created or destroyed but can
change forms.
 When energy changes forms, we call this an energy conversion.
 Potential is energy which is stored and kinetic is the energy of motion.
 Thermal energy is involved in nearly all energy conversions.
 Temperature is the measure of the average kinetic energy (speed) of the particles
 Temperature does not depend on the amount of substance.
 Thermal expansion is the increase in volume of a matter due to an increase in
temperature.
 Thermal energy is the total amount of kinetic energy and depends on temperature, mass,
and the type of substance.
 A substance at a lower temperature can have more thermal energy than a substance at a
higher temperature if the substance at a lower temperature has a greater mass.
 Specific heat refers to the amount of heat needed to raise the temperature of one gram of
substance one degree Celsius.
 Water has a high specific heat.
 The Heat of Fusion refers to the energy needed to change the state of matter from solid to
liquid or vice versa.
 During a change in state, there is no change in the temperature. Temperature changes
occur when matter is not changing state.
 Convection currents occur in liquids and gases due to differences in heating. Warmer less
dense matter rises and cooler denser matter sinks.
 Conduction is heat transfer that occurs what particles are in direct contact and collide with
each other.
 Radiation is heat transfer that occurs when thermal energy travels as a wave. It is the only
form of heat transfer that can occur in the vacuum of outer space.
Motion
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If you know the distance and time an object has traveled, you know its speed.
If you have the speed and direction of an object’s motion you know its velocity.
Speed = Distance/Time
Acceleration is the rate at which velocity changes.
Acceleration = (Final velocity – Initial velocity)/Time
Steepness of a slope depends on how fast the object is moving.
Constant speed on a motion graph is represented by a straight diagonal line.
Constant acceleration on a speed/time graph is represented by a straight diagonal line.
A horizontal line on a motion graph means the object is at rest.
A horizontal line on a speed/time graph means constant speed (not accelerating).
A curved line on a motion graph means changing speed.
A curved line on a speed/time graph means changing acceleration.
Forces
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Net Force is the overall force acting on an object
Unbalanced forces acting on the same object produce a change in motion
Balanced forces do not produce a change in motion
Inertia is the tendency of an object to resist a change in motion (depends on mass)
Friction depends on the types of surfaces involved and the forces pushing them together
Gravity depends on the mass of the objects and the distance between them
Weight is the force of gravity on a person or object
Newton’s 1st Law states that an object at rest stays at rest; an object in motion continues
moving at a constant velocity, unless acted on by an unbalanced force.
Newton’s 2nd Law states that the net force on an object is equal to the product of the mass
and acceleration. Formula is Force = Mass x Acceleration.
Newton’s 3rd Law states that for every action force there is an equal and opposite reaction
force.