Physical Sciences: Matter, Motion, Energy, and Waves
The Physical Sciences domain on the NYS Grade 8 Science test samples matter and its interactions, motion and stability, energy, and waves. Items ask you to explain phenomena with the particle model, analyze forces and motion, trace energy transfer, and interpret wave data. Many questions pair a core idea with a practice such as analyzing data or constructing an explanation, so name the evidence you used.
Core rules
- All matter is made of particles too small to see. In a closed system, mass is conserved during physical and chemical changes; in an open system, gases can enter or leave and the measured mass can change.
- A net force changes an object’s motion. Balanced forces produce no change in velocity, so a moving object with zero net force keeps moving at constant speed in a straight line. Unbalanced forces cause acceleration.
- Energy is conserved: it transfers between objects and transforms between forms, such as gravitational potential energy to kinetic energy in a falling object.
- Waves transfer energy, not matter. Amplitude relates to energy; frequency relates to pitch or color; for a fixed wave speed, wavelength and frequency are inversely related.
- A chemical change produces new substances with different properties; a physical change does not change the identity of the substance.
Worked example
A sealed bottle contains 5.0 g of baking soda and 50.0 g of vinegar, for a total mass of 55.0 g. After the reaction, the closed bottle still has a mass of 55.0 g. When the cap is opened, the mass drops.
Reasoning: the reaction produces carbon dioxide gas. In the closed system, the gas cannot escape, so the total mass of all matter is conserved. Opening the cap creates an open system, and gas leaves; the missing mass is still matter, now in the air. This is not destruction of matter.
Traps that cost marks
- Claiming a force is needed to keep an object moving at constant speed.
- Explaining a mass decrease as “matter destroyed” instead of gas escaping the system.
- Confusing amplitude with frequency: a louder sound has greater amplitude, not higher pitch.