thermal energy theory

why does a wool jumper keep someone warm

it insulates the upper body and reduces the heat produced by the body from escaping. the jumper traps air between its fibres and reduces heat loss because air and wool are poor conductors of heat

why do people wearing a jumper feel hot after running

exercise cause the body to produce extra internal energy which must be released to the surroundings as heat. this heat is trapped by a jumper giving the person the sensation of feeling hot and uncomfortable

why can u tell the direction that a wind is blowing by holding up a wet finger

the breeze causes moisture from the part of u finger facing the wind to evaporate more than usual. this has a cooling effect on that part of your finger

why does sea breeze blow inland during the day but towards the ocean during the night

a water mass such as the ocean heats up and cools more slowly than a large land mass. during the day land heats up quickly, warm air above it rises and cool air from the ocean moves inland to replace it. the opposite occurs in the evening

why can a refrigerator be referred to as a heat pump

a refrigerator cools the contents on the inside by transferring the heat (through the condenser unit) to the outside. essentially its pumping heat out. you will notice that the back of a refrigerator is always warm

whats the process leading to change in air temp around an evaporator in a heat pump in terms of kinetic theory

• Evaporator turns liquid into gas. Energy is required for the particles to separate from particles in the liquid and become free to move randomly.

• Energy is absorbed from the surrounding air particles. The average kinetic energy of the air particles decreases.

• Temperature is a measure of the average kinetic energy of the particles and hence the temperature of the air decreases, i.e. cooler air is produced.

what happens to the internal energy of particles during the melting process

internal energy increases due to potential energy increasing.The energy is used to overcome the attractive forces between the particles in the solid lattice so they can move more freely in the liquid state.