What the ASVAB is actually testing
Physics questions on GS test four areas: Newton's laws of motion, energy and work, waves and sound, and heat transfer. You don't need calculus — you need the right formula, clean substitution, and a solid understanding of the vocabulary. Most physics questions give you two numbers and ask for a third.
Newton's three laws
- 1st Law (Inertia): An object at rest stays at rest; an object in motion stays in motion — unless acted on by a net external force. This is why you lurch forward when a vehicle brakes.
- 2nd Law: F = ma. Net force equals mass times acceleration. Bigger mass means more force required to produce the same acceleration.
- 3rd Law: Every action has an equal and opposite reaction. When you fire a weapon, the recoil is the reaction force.
Work, energy, and power
Work only happens when a force causes displacement in the direction of the force. Holding a weight overhead involves force — but if you're not moving it, you're doing zero mechanical work.
Energy comes in two key forms:
- Kinetic energy (KE): energy of motion — KE = ½mv². Double the speed, quadruple the kinetic energy.
- Potential energy (PE): stored energy — PE = mgh. Taller position, more potential energy.
Power is the rate of doing work. A motor that does the same job in half the time is twice as powerful.
Waves
Waves transfer energy without transferring matter. Key vocabulary:
| Term | Meaning |
|---|---|
| Frequency (f) | Cycles per second (Hertz) |
| Wavelength (λ) | Distance between wave peaks |
| Amplitude | Height of the wave (intensity/loudness/brightness) |
Higher frequency = shorter wavelength (at a given speed). Sound waves are longitudinal (particles compress); light waves are transverse (electromagnetic).
Heat transfer
Heat moves in three ways:
- Conduction — direct contact (metal handle heats up)
- Convection — fluid circulation (boiling water, wind patterns)
- Radiation — electromagnetic waves through space (heat from the sun)
Study approach
Memorize the five formulas in the reference block above. Practice plugging in numbers — the arithmetic on GS physics is usually simple once you have the right equation. Focus on understanding what each law describes qualitatively so you can answer concept questions without calculation.