Particle model Flashcards – Cambridge IGCSE (9–1) Physics 0972 (Extended) (2026–2028)

How is a substance’s temperature related to its particles’ average kinetic energy?

Higher temperature means greater average kinetic energy; lower temperature means less.

What happens to particle motion when a substance’s temperature rises?

The motion becomes more vigorous.

What is absolute zero, in degrees Celsius?

The lowest possible temperature: $-273\,^{\circ}\mathrm{C}$.

What is the kinetic energy of particles at absolute zero?

They have their least possible kinetic energy.

How do randomly moving gas particles produce pressure on a surface?

Collisions change the particles’ motion and exert forces on the surface. The combined force per unit area is the pressure.

For a fixed amount of gas at constant volume, how does raising the temperature affect pressure?

Pressure increases: particles move more, making wall collisions more frequent and more forceful.

For a fixed amount of gas at constant temperature, how does reducing the volume affect pressure?

Pressure increases because collisions with the container walls become more frequent.

What is Brownian motion?

The random, irregular motion of microscopic particles suspended in a gas or liquid.

What causes suspended particles to move unpredictably in Brownian motion?

They are continually struck unevenly from different directions by much smaller particles of the surrounding gas or liquid, changing their speed and direction.

What does Brownian motion provide evidence for?

The kinetic particle model: particles in the surrounding matter are in continuous, random motion.