science

Physical Science Exam Review (Ch. 6–9)

Scientific Method

• Observation

• Question

• Hypothesis

• Experiment

• Collect Data

• Analyze Results

• Conclusion

Simple Machines

• Lever

• Pulley

• Wheel and Axle

• Inclined Plane

• Wedge

• Screw

• Perfect machine = 100% efficiency

Work, Power, and Machines

• Work: force applied over a distance

• Power: rate at which work is done

• Efficiency: output work ÷ input work

• Mechanical Advantage: output force ÷ input force

• Gear Ratio: output turns ÷ input turns

• Horsepower = 746 watts

• Watt = unit of power

Energy

• Kinetic Energy: energy of motion

• Potential Energy: stored energy due to position

• Mechanical Energy: motion or position

• Chemical Energy: stored in molecules

• Radiant Energy: electromagnetic energy

• Nuclear Energy: stored in atomic nuclei

• Law of Conservation of Energy: energy cannot be created or destroyed

Units & Conversions

• Distance: meters

• Mass: grams

• Force: newtons

• Energy: joules

• Power: watts / horsepower

• 1 kg = 1000 g

• 1 m = 100 cm

• Density = mass ÷ volume

• Speed = distance ÷ time

Newton’s Laws of Motion

• 1st Law (Inertia): objects stay at rest or motion unless acted on

• 2nd Law: F = m × a

• 3rd Law: every action has an equal and opposite reaction

Forces & Motion

• Inertia depends on mass

• Friction opposes motion

• Unbalanced forces cause motion

• Net force = total force acting on object

• Force and acceleration: direct relationship

• Force and mass: direct relationship

• Mass and acceleration: inverse relationship

• Acceleration due to gravity = 9.8 m/s²