Science Trimester 2 Exam

Science Trimester 2 Exam

1. Gas Laws

   • Pressure
     • The amount of force per unit area.
       • SI unit for pressure: Pascal, but kilo pascal is usually used
   • What does the amount of force exerted by a gas depend upon?
     • The size of the container
       • How will particles move in an open container vs. a closed container?
         • Open - They would come out of the container Closed - They would try to spread as far apart as possible
   • Boyle's Law
     • With the temperature held constant, when the pressure of a gas increases the pressure will decrease
   • Charles's Law
     • With pressure held constant, when the gas is heated, the volume will increase
   • Absolute Zero
     • The temperature at which particle motion stops
     • -273 C
   • Buoyancy
     • The ability of a fluid to exert an upward force on an object immersed in it
       • Explain how a hydraulic lift works
         • Two cylinders connected by a pipe are filled with oil. If you push down on one piston, then it pushes the oil into the pipe and lifts the other piston and whatever weight is put on it.
         • Uses Pascal's principle
     • Archimedes Principle
       • The buoyant force of an object in a fluid is equal to the weight of the fluid displaced by the object
   • Bernoulli's Principle
     • As the velocity of a fluid increases, the pressure exerted by the fluid decreases

2. Energy

   • Difference between potential and kinetic
     • Potential: stored Kinetic: in motion
   • Matter is anything that takes up space and has mass
     • Solid
       • Very Strong Attractive Force
         • Atoms can wiggle a little
           • Solid becomes liquid at melting point
             • Heat of Fusion
               • Amount of energy it takes to change 1kg of a solid to a liquid at its melting point
           • Solid to gas w/o liquid is sublimation
     • Liquid
       • Medium Attractive Force
         • Particles can move over and around each other
           • Liquid to gas is evaporation
             • Changes at its boiling point.
     • Gas
       • No attractive force
         • Particles move freely
           • Gas to liquid is condensation
             • Kinetic Theory of Matter Particles are in constant motion Rate of motion depends on attractive force Attractive force defines state of matter
     • Plasma
       • Stars
   • Faster atoms move=more kinetic energy=higher temp.
     • Temperature
       • Average kinetic energy of all the particles in an object
         • SI unit for heat is joules
     • Thermal Energy
       • total amount of kinetic energy in all the particles in an object
       • Transferring
         • Conduction: direct contact
         • Convection: energy in a current
         • Radiation: electromagnetic waves
     • Heat flow: warm to cold

3. Work

   • The transfer of energy through motion
     • Formula: work=(force)(distance)
       • Joule (Newton*Meter)
   • Positive Work
     • Motion in the same direction as the force
   • Negative Work
     • Motion in the opposite direction of the force
   • No Work
     • Force is at a right angle to the motion
     • No motion

4. Simple Machines

   • a device that makes work easier
     • changes size/direction of force
   • 6 Types
     • Ramp
       • a sloped surface used to lift heavy objects
     • Wedge
       • a moving inclined plane
     • Screw
       • an inclined plane wrapped around a cylindrical post
     • Lever
       • a bar that is free to turn around a fixed point
         • 1st class lever
           • Fulcrum is between effort and load
             • Use it in a pan balance. Increases force + distance
         • 2nd class lever
           • load is between fulcrum and effort
             • Use it in a wheelbarrow. Increases force.
         • 3rd class lever
           • Effort is between fulcrum and load
             • Use it in a baseball bat. Increases speed
     • Wheel & Axle
       • a lever with two wheels that rotate together
   • Mechanical advantage: comparison of effort force to resistance force. You want a high number.
     • There is never a truly ideal machine because the work out is never the same as the work in b/c of friction

5. Mixtures & Solutions

   • Element - substance where all the atoms are the same
     • Compound - a substance made up of two or more elements
       • Mixture - a material made up of two or more substances
         • Two types
           • Heterogeneous
             • Substances are visible
           • Homogeneous
             • Substances are not visible
         • Suspension
           • Particles settle over time
         • Colloid
           • Particles don't settle over time
           • Tyndall effect
             • Light shines through it = colloid
       • How can the rate of dissolving be increased?
         • 1. Stirring
           • 2. Increasing temperature
             • 3. Start with smaller particles