S3 PHY 2.1

According to the particle model of matter:

The average kinetic energy of molecules in a body can be inferred by measuring the temperature of the body. When the molecules possess more kinetic energy and move more rapidly, the temperature of the body increases.

As temperature increases, the kinetic energy (KE) of molecules also increases. At lower temperatures (e.g., 5°C), molecules are closely packed and have less motion. At moderate temperatures (e.g., 30°C), molecules are more spread out and exhibit more motion. At higher temperatures (e.g., 90°C), molecules are much more spread out and have significantly increased motion.

The purpose of the activity is to observe how temperature affects the diffusion of food coloring in water. It demonstrates that food coloring spreads more quickly in hot water compared to cold water due to the increased kinetic energy of the molecules in the hot water.

Molecules in hot water move more quickly, allowing the food coloring to spread faster due to higher kinetic energy.

Temperature is a measure of the average kinetic energy of molecules in a body; at the same temperature, molecules have the same average kinetic energy.

Absolute zero is the temperature at which the average kinetic energy of molecules reaches its minimum value, approximately -273 °C, and nothing can be colder than this temperature.

False. A body at rest can still have molecular kinetic energy due to the random motion of its molecules.

False. Molecules in a body at a certain temperature have a range of kinetic energies.

The unit of internal energy, heat, and work is joule (J).

False. Temperature measures the average kinetic energy, not the total kinetic energy.

True. The average kinetic energy of molecules in A is higher due to the higher temperature.

False. While the average kinetic energy is higher in A, individual molecules can have overlapping energy ranges.

The internal energy of a body is the total amount of the molecular energy stored in the body, which includes the total kinetic energy due to the random motion of molecules.

Internal energy is measured in joules (J), with larger units including kilojoules (kJ) and megajoules (MJ).

The internal energy of a body increases with both temperature and mass, as it includes the total kinetic energy of all the molecules in the body.

The unit prefixes for energy measurement include:

The prefixes are case-sensitive, meaning that 1 mJ (milliJoule) is not equal to 1 MJ (MegaJoule).

The frozen lake is likely to have a higher total molecular kinetic energy because, despite the hot chocolate having a higher temperature and average molecular kinetic energy, the lake has a much larger mass and therefore a greater number of molecules contributing to its total molecular kinetic energy.

Heat is the energy transferred from one body to another as a result of a temperature difference. It is represented by the symbol Q and measured in joules (J).

The rate of energy transfer depends on the temperature difference; the larger the temperature difference, the higher the rate of energy transfer.

James Joule (1818-1889) demonstrated that 'heat' is a form of energy and not a substance, contributing significantly to the understanding of energy transfer.

Heat flows naturally from high-temperature bodies to low-temperature bodies until thermal equilibrium is reached.

The coffee loses energy and its temperature decreases, while the cup gains energy and its temperature increases until they reach the same temperature.

Thermal equilibrium occurs when two bodies reach the same temperature, and energy transfer stops.

In physics, only heat (energy) is transferred from a hot body to a cold body; there is no such quantity as 'coldness'.

Heat refers to the energy that transfers between two bodies, not the energy stored in a body. The energy stored in a body is described as internal energy.

Examples include:

1. Rubbing hands together
2. Shaking a bottle of water
3. Hitting a metal with a hammer

Internal energy is the total energy stored in a system, calculated as the sum of the total kinetic energy (KE) and total potential energy (PE) of all the molecules in the object.

Internal energy = total KE of all molecules + total PE of all molecules

Internal energy can be increased by:

1. Transferring heat to the object
2. Doing work done on the object

Temperature is a measure of the average kinetic energy (KE) of molecules in a body. For two bodies at the same temperature, their molecules have the same average molecular KE.

The average kinetic energy of matter in solid state and liquid state is the same if they have the same temperature.

Absolute zero is -273°C, the point at which the average kinetic energy of molecules reaches its minimum value. Nothing can be colder than -273°C.