re inside the ball.\n\nExplain, in terms of gas particles, why the pressure inside the ball has increased.","markscheme":"- States that thermal energy is transferred to the gas particles, increasing their average kinetic energy B1\n- States that gas particles move with a higher average speed B1\n- Explains that particles collide with the inside walls of the ball more frequently B1\n- Explains that particles collide with a greater force, increasing the pressure ($p = \\frac{F}{A}$) B1","marks":4,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"particle_model","label":"Particle-model explanation","steps":[{"type":"text","order":0,"title":"Start with energy transfer","content":"The hot sun transfers **thermal energy** to the gas inside the ball. Thermal energy is energy transferred because of a temperature difference.\n\nThis makes the gas particles' **average kinetic energy** increase. Kinetic energy is the energy an object has because it is moving. **This earns the first B1 mark.**","highlights":[{"text":"increase in temperature inside the ball","location":"specification"}]},{"type":"text","order":1,"title":"Link energy to speed","content":"A greater average kinetic energy means the gas particles have a **higher average speed**. They are still moving randomly in all directions, but they move faster on average.\n\n**This earns the second B1 mark.**"},{"type":"text","order":2,"title":"Describe more collisions","content":"Because the particles move faster, they reach the inside walls of the ball more often. Therefore, the particles collide with the walls **more frequently**.\n\n**This earns the third B1 mark.**"},{"type":"text","order":3,"title":"Link force to pressure","content":"Each faster particle changes momentum more rapidly when it bounces from the wall, so **each collision is with a greater force**. Therefore the gas exerts a greater force on each unit area of the ball wall, so its pressure increases:\n\n$$p=\\frac{F}{A}$$\n\nThis earns the final B1: greater force from the collisions gives greater pressure.","highlights":[{"text":"Explain, in terms of gas particles, why the pressure inside the ball has increased.","location":"specification"}]}]}],"generatedAt":"2026-07-21T05:19:05.375Z","modelVersion":"gpt-5.6-terra","explanationVersion":"v3"},"options":[]},{"id":"0ec13178-4dd4-4bc2-b046-dcc7e3950914","label":"b","content":"A student writes down a simple model of atmospheric pressure:\n\n* The atmosphere is made up of gas molecules colliding with objects.\n* The density of the air is assumed to be uniform.\n* The atmospheric pressure increases as the altitude above the ground increases.\n\nThe student has made **one** mistake in this model.\n\nIdentify the wrong word and write the correct word to replace it.\n\nWrong word:\nCorrect word:","markscheme":"- Identifies the wrong word as \"increases\" B1\n- Identifies the correct word as \"decreases\" (or \"falls\" / \"drops\") B1","marks":2,"order":1,"markingRubric":null,"explanation":{"methods":[{"id":"pressure_model","label":"Check the pressure trend","steps":[{"type":"text","order":0,"title":"Picture the atmosphere","content":"Air molecules collide with objects and produce pressure. Higher above the ground, there is less air above you, so its weight produces less pressure.","highlights":[{"text":"The atmosphere is made up of gas molecules colliding with objects.","location":"specification"},{"text":"The atmospheric pressure increases as the altitude above the ground increases.","location":"specification"}]},{"type":"text","order":1,"title":"Correct the trend","content":"The statement says pressure **increases**, but this is the mistake. Atmospheric pressure **decreases** as altitude increases.\n\nWrite:\n\nWrong word: **increases**\n\nCorrect word: **decreases**\n\nIdentifying **increases** earns B1; replacing it with **decreases** earns B1.","highlights":[{"text":"The atmospheric pressure increases as the altitude above the ground increases.","location":"specifica

Pressure

Question 22

Pressure Questions

Pressure

Question 22

Pressure Questions