What does temperature actually measure at the particle level?

The total thermal energy stored in all the particles The average kinetic energy of particles in the substance The pressure exerted by particles on the container walls The density of particles per unit volume

The SI unit of temperature is the Kelvin. What is 25 °C converted to Kelvin?

25 K 248 K 298 K 373 K

A large lake and a small cup of boiling water are both at 100 °C. Which object contains more thermal energy, and why?

The cup of boiling water, because it is at a higher temperature than the lake They contain the same thermal energy because they are at the same temperature The lake, because thermal energy depends on the total number of particles, not just temperature The cup, because boiling water releases energy rapidly

Water has a specific heat capacity of 4,186 J/kg·K. How much energy is needed to raise 2 kg of water by 10 °C?

4,186 J 41,860 J 83,720 J 837,200 J

Why do coastal cities generally have milder climates (smaller temperature swings between summer and winter) than inland cities at the same latitude?

Coastal cities receive more rainfall, which cools the air in summer Sea breezes carry cold Arctic air inland every night Water's very high specific heat capacity means oceans absorb and release large amounts of heat with little temperature change Coastal soil contains more salt, which reduces thermal expansion

Which of the three heat transfer mechanisms requires no material medium and can operate through a vacuum?

Conduction Convection Radiation Transpiration

Metals are good thermal conductors because:

Their atoms are packed more closely together than in non-metals They have free electrons that can rapidly carry kinetic energy through the material Metal atoms vibrate at a lower frequency, reducing energy loss Metals reflect infrared radiation internally, trapping heat

A civil engineer must install expansion joints in a 500 m steel railway track that experiences temperatures ranging from −10 °C to +50 °C. The thermal expansion coefficient of steel is 12 × 10⁻⁶ /°C. How much does the track expand across this 60 °C range?

0.036 m 0.36 m 3.6 m 36 m

Natural convection in a room heated by a radiator relies on which physical principle?

Hot air molecules move faster and push cold air upward by direct collisions Warm air expands, becomes less dense, rises, and is replaced by cooler, denser air from below The radiator emits microwaves that heat the ceiling first Thermal radiation from the radiator directly heats distant walls

A Thermos flask (vacuum flask) minimises heat transfer using multiple strategies. Which combination does it use?

Thick foam layer (reduces conduction) plus airtight lid (prevents evaporation) Vacuum jacket (eliminates conduction and convection) plus silvered walls (minimises radiation) Copper inner wall (high conductivity) plus polystyrene outer shell (insulation) Double glass walls filled with argon gas (low conductivity)

The R-value of an insulation material is a measure of:

Its capacity to store heat per kilogram The rate at which it reflects infrared radiation Its resistance to heat flow; a higher R-value means better insulation The temperature at which the material begins to conduct electricity

Double-glazed windows reduce heat loss compared to single glazing primarily because:

The second pane reflects all infrared radiation back into the room Two layers of glass are twice as thick, halving conduction through the glass itself The trapped gas layer between the panes has very low thermal conductivity and eliminates convection at that gap The window frame acts as a heat sink, absorbing energy before it enters the room