Science Finals G9

• Momentum


  Quantity of motion of an object, depends on mass and velocity
• Aside from mass, velocity affects the momentum of an object's motion
• A greater force creates a large change in momentum
• Momentum unit


  kg m/s
• In any system with 2 objects, the loss of momentum of one object equals the gain in momentum of the other objects
• The total momentum and energy before collision is equal to the total momentum and energy after collision
• The KE of an object is directly proportional to the square of its velocity
• Energy conservation


  When the sum of all forms of energy is constant
• Isolated system


  KE and PE are the only forms of energy present
• A stretched rubber band does not possess KE
• A drum rolling down an inclined plane possesses both KE and PE
• No machine is 100% efficient
• When a rifle fires a bullet the rifle will recoil, this illustrates conservation of momentum
• Generator


  Device that converts mechanical energy into electrical energy
• Transformer


  Device used to lower or raise the output voltage from an input AC voltage
• A generator is used in the generation stage of providing electricity to consumers
• Power loss in the transmission of electricity occurs due to the resistance of long transmission wires
• Stages before electricity reaches consumers

  1. Transmission

  2. Distribution
• The higher the voltage at which electricity is transmitted, the lower the current
• Step-down transformer


  Equipment that reduces power loss during the transmission of electricity from a power plant to a substation
• National Grid


  Network of transmission lines all over the country
• Powerplant


  Facility for the generation of electricity from energy sources
• Wind or falling water turns the turbine in a kinetic power plant
• Nuclear power plant


  Thermal power plant
• The momentum of a system can change due to its interaction with another system
• Motor vehicle collision is one of the most common causes of injury, death, and property damage
• Vehicles that are well-designed and well maintained are safe to drive
• Poor road conditions have a significant contribution to road accidents
• The motion of a projectile is influenced only by a downward force of gravity
• When work is done on an object, energy is wasted
• The greater the amount of wasted energy, the lower the efficiency of the machine
• Energy is the ability to do work
• Heat can do work