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Flashcards in chapter5-energy Deck (34)
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1

when does scientist start to understand energy?

1800

2

what is internal energy?

result of forces between the atoms and molecules of a system.

3

example for internal potential energy?

body fat and glycogen.

4

example for mechanical energy

water wheel

5

what is metabolism?

use body to convert stored chemical energy in food

6

how electrons moves?

from - to +

7

examples of radiant energy?

radio waves , ultraviolet waves and microwaves.

8

example of electrical energy?

lamps-->light.
toaster-->heat.
lamp and toaster属于radiant energy
blender-->mechanical energy

9

example of radiant energy?

electric coils, charcoal grills and gas flames-->cook food.

10

what does magnetron do?

electrical energy-->microwaves.

11

how does microwave travel? how they reflected?

straight lines, reflected by metals

12

what does microwave cause?

polar compound(water) to vibrate--> friction-->heat
more water in food, faster the food will cook
also quick if food are high in sugar and fats

13

what are low frequency long wavelength?

radio wave
microwave-->cook
infrared wave-->heat, only absorb in the surface

14

what are high frequency short wavelength?

UV-->kill bacteria, food preservation, produce VD
X ray
gamma ray-->food preservation: irradiation, destroy living organisms could cause spoilage

15

what is the frequency of rapid electrical pulse? what does it do?

10000per second.
kill microorganisms and inactive enzymes that present in food.

16

what does induction cooktops use?

electromagnetic waves to generate heat in food.-->special pan need--> current crate magnetic field-->produce low electric current-->heat时间更短

17

microwave safety. 5 points

vent plastic wrap used to cover food container
pierce whole fruit and veges have tough, unbroken skins
never hard-cook or soft-cook eggs in their shell
no aluminum foil-->cause sparks to jump from foil to walls.
no metals

18

what is the cancer causing substance name?
how to prevent?

-carcinogens-->when meat grilled. not vege and fruits
-no more than 1-2 per week, use gas to grill
-clean grill before use
-bone-side down
-add vinegar or lemon juice speed cooking
-reduce grill time-precook,use marinades 10%soy sauce and 1%sugar decrease 60% carcinogens.
-turn by tongs , not folk reduce dripping, which cause flame flare-ups

19

what are factors influence individual's calorie?

hormones
activity level
type of food
mineral level
age
sex
sleep level
genetics
stress
illness

20

what is basal metabolism?

body need calories to support basic functions such as breathing, blood circulation and cell growth and repair.
突然降低或升高10%体重会降低新陈代谢

21

what are 2 factors make up the balance of your daily calorie need?

physical activity and energy used to process the food you eat

22

why food scientist measure food energy?

know capacity to produce heat

23

what is heat capacity?
how is water's heat capacity?

ability to absorb heat
greatest

24

what cause a convection current?

fluid heat-->molecules push farther apart-->density of fluid decrease

25

what does convection use?

boil water
baking

26

what cooking method use radiation?

broiling and rotisserie cooking

27

when is sublimation use?

in food industry to freeze and dry food at same time

28

sublimation?

solid to gas

29

deposition?

gas to solid

30

what is dry ice?

solid carbon dioxide