A beaker of water is heated from the bottom using a hot plate. A small, sealed flexible plastic packet containing nitrogen gas is submerged in the water.
When the hot plate is turned on, the temperature of the water at the top of the beaker soon begins to increase, even though the heat source is at the bottom. Explain how this thermal energy is transferred to the top of the beaker.
As the temperature of the nitrogen gas inside the packet increases, the packet expands, increasing its volume. (i) State what happens to the motion of the nitrogen molecules as the temperature increases.
As the packet expands, the pressure of the nitrogen gas remains constant (equal to the external atmospheric pressure). Explain, in terms of gas molecules, how the pressure of the nitrogen remains constant.
321 exam-style questions on CIE IGCSE Physics 2.1 Kinetic particle model of matter, covering 2.1.1 States of matter and changes of state, 2.1.2a Particle structure and motion in solids, liquids and gases, 2.1.2b Gas pressure and particle collisions, 2.1.2c Brownian motion, 2.1.3a The absolute scale of temperature, and 2.1.3b Pressure, volume and temperature of a gas. Each one has a worked solution and a mark scheme showing where the marks go.