Quarter 3 Science 8 Exam Reviewer

Exam Structure

  • Focus on key concepts, definitions, and problem-solving strategies.

Multiple Choice Questions

  • Net force on a stationary book: Zero, forces are balanced.

  • Force opposing motion: Friction.

  • Force needed for circular motion: Centripetal force.

  • Example of Kinetic Energy: A bird flying.

  • Process of light dispersion in a prism: Dispersion.

  • Color bent least in light spectrum: Red.

  • Newton's First Law: Object resists changes in motion.

  • Sound wave speed medium: Solid.

  • Factor affecting sound wave speed: Temperature of the medium.

  • Temperature measures: Average kinetic energy of particles.

  • Heat movement: From higher to lower temperature (Heat transfer).

  • Heat needed to raise temperature: Specific heat.

  • Energy of bodies in motion: Kinetic energy.

  • Net heat transfer stops when: Thermal equilibrium is reached.

  • Copper-bottom pans: Low specific heat capacity for quick heating.

  • Process of liquid to solid: Solidification/Freezing.

  • Movement of charged particles: Electric current.

  • Electric pressure causing current to flow: Voltage.

  • Devices producing current: Generators, electric cells, solar cells.

  • Standard unit for electric current: Ampere (A).

  • Ohm's Law relationship: V=IRV = I R.

  • Work defined by: Magnitude of displacement and force parallel to it.

  • Effect of an open circuit in series: Current stops flowing.

  • Resistance property: Proportional to length, inversely to cross-sectional area.

  • Electric bill measure: Kilowatt-hours (kWh).

  • Kilowatt-hour unit: Product of Power and Time.

  • Efficient refrigerator factor: Highest Energy Efficiency Factor (EEF).

  • Safe electric usage tip: Avoid overloading outlets.

  • Force producing acceleration: Has magnitude and direction.

  • Heating material effects: Generally causes expansion.

Problem Solving Strategies

  • Newton's Second Law Example:

    • Given: Net Force = 150 N, Mass = 40 kg.

    • Formula: Fnet=maF_{net} = ma; Calculate a=150 N40 kg=3.75 m/s2a = \frac{150 \text{ N}}{40 \text{ kg}} = 3.75 \text{ m/s}^2.

  • Gravitational Potential Energy Example:

    • Given: Mass = 5 kg, Height = 1.5 m, g = 9.8 m/s².

    • Formula: PE=mghPE = mgh; Substitute to find PE=(5.0 kg)(9.8 m/s2)(1.5 m)=73.5 JPE = (5.0 \text{ kg})(9.8 \text{ m/s}^2)(1.5 \text{ m}) = 73.5 \text{ J}.

  • Heat Transfer Example:

    • Given: Mass = 1.5 kg, Initial T = 30°C, Final T = 80°C, Specific heat = 4186 J/kg°C.

    • Formula: Q=mcΔTQ = mc\Delta T where ΔT=T<em>f−T</em>i\Delta T = T<em>f - T</em>i; Calculate heat added: Q=(1.5 kg)(4186 J/kg°C)(50 °C)=313,950 JQ = (1.5 \text{ kg})(4186 \text{ J/kg°C})(50 \text{ °C}) = 313,950 \text{ J}.

  • Ohm's Law Example for Resistance:

    • Given: Voltage = 110 V, Current = 10 A.

    • Formula: R=VIR = \frac{V}{I} gives R=110 V10 A=11 OhmsR = \frac{110 \text{ V}}{10 \text{ A}} = 11 \text{ Ohms}.

    • Power Calculation: P=IV=(10 A)(110 V)=1,100 WP = IV = (10 \text{ A})(110 \text{ V}) = 1,100 \text{ W}.