Heat Transfer (1/29) Flashcards
(33 cards)
What is heat?
energy
What are the two main types of energy?
kinetic energy and thermal energy
What is kinetic energy?
movement of molecules so that when they bump into each other, energy is converted from one form to another
What is thermal energy?
energy as heat
What is the measurement of thermal energy?
temperature
What type of energy do we use to cook food?
thermal energy
What does cooking food do?
improves food safety, extends shelf life, makes foods edible, improves digestibility, and can enhance sensory properties
What is sensible heat?
heat you can feel/measure
The physical state of matter changes as a result of what?
energy in the form of heat, such as solid (ice), liquid (water), and gas (steam)
What creates vapor pressure?
gaseous molecules hovering over water
What forms in a liquid as the vapor pressure is increased to a point greater than the atmospheric pressure
bubbles
What interacts with cooking?
outside pressure
When does water boil?
at sea level at 212 F and at lower temps at higher elevations
What is heat capacity?
how much energy it takes to heat things by a specific temperature change
What is the heat capacity for water?
1 cal/g C
What is latent heat?
heat required to change state without changing temperature
What do you have to add to cause a change in state?
energy
What needs more energy ice to change to liquid water or water to change to steam?
water to steam (540 calories)
What are the different techniques used to transfer heat to food for cooking?
conduction, convection, radiation, and induction
What is conduction?
direct contact: frying pan on a stove top
What is convection?
currents in the air or liquid distributive the heat
What is radiation?
energy transferred as waves or rays vibrating at a high frequency
What is induction?
magnetic current generated by a high-frequency induction coil
What happens when liquid and gases are heated?
they become lighter (less dense) and rise, whereas cooler molecules of the liquid or gas move to the bottom of a container or closed compartment
