unit 4

Question 1

lesson 10

newtons 2nd law and formula

Answer 1

at any time the net force on a body is equal to the body’s acceleration multiplied by its mass

F=mXa

Question 2

lesson 10

work done on a object

Answer 2

for a given amount of force (f) and a given distace (d) the work (in joules) done on an object is given by the formula –> W=Fxd

Question 3

lesson 10

power def and formula

Answer 3

the rate at which work is done. the formula for power in watts is given by work and the time
P=w/t
(1 watt of power = 1 joule per second) –> 1 W = 1 J/s

Question 4

energy def

Answer 4

the physical quantity that measures the ability of a body or system to perform work and therefore to modify its position or state

measured in joules

Question 5

lesson 10

mechanical energy

Answer 5

the energy a body posseses due to its motion or position

Question 6

lesson 10

kinetic energy - what it is and formula

Answer 6

energy a body has due to its motion
KE = 1/2mv^2
m= mass (kg)
v= velocity (m/s)

measured in joules

Question 7

lesson 10

potential energy and equation

Answer 7

energy a body has due to its position

PE=mgh
m= mass kg
g= gravity force (m/s^2)
h=height (m)

measured in joules

Question 8

lesson 10

universal principle of energy conservation

Answer 8

energy in the universe cant be created or destroyed it can only change forms. if no force is exerted on a body, the following condicition must be met:
Eci + Epi = Ecf + Epf

Question 9

lesson 10

characteristic of all types of energy

Answer 9

• all energy has the capacity to perform work measured in joules
• all energy fulfills the principle of energy conservation

Question 10

lesson 10

types of energy

Answer 10

according to where the energy is store
1. thermal energy: energy due to to moving particles (measured by temp)

2. chemical energy: energy stored in chemical bonds btw the atoms that make up matter. when matter particles in a chemical reaction, it can release energy, store energy, transform into another type of energy or perform work

Question 11

lesson 10

chemical energy - ATP molecule

Answer 11

• in cells energy is mainly stored in ATP
• ATP is a nucleotide made up of adenine + ribose + 3 phosphate groups

Question 12

lesson 10

exothermic or exergonic reactions

Answer 12

exothermic or exergonic reactions release energy

reactants –> products + energy

Question 13

lesson 10

endothermic or endergonic

Answer 13

endothermic or endergonic reactions absorb energy
reactants + energy –> products

Question 14

lesson 10

catabolic reactions

Answer 14

• a type of exothermic reactions
• organic nutrients are broken down and transformed into simple products, extracting the chemical energy stored in their bonds
  nutrients –> simple products + energy
• in cells this released chemical energy is stored in the ATP molecules
  Glucose + ADP + Pi –> ATP + piruvate

Question 15

lesson 10

anabolic reactions

Answer 15

• a type of endothermic reaction
• complex molecules are built up from numerous simple ones

Question 16

lesson 10

enzymes - activation energy

Answer 16

an initial amount of energy must be applied to carry out a reaction.
the initial energy is required to iniate the reaction = activation energy

reactions w higher activation energy will be slower compared to reactions w low activation energy

Question 17

lesson 10

enzyme - catalyst

Answer 17

chemical substances that are capable of lowering the activation energy of the reaction and increase the reaction rate, without participating in the chemical reaction itself

Question 18

lesson 10

enzyme and catalyst relationship

Answer 18

enzymes are biological catalyst –> proteins that lower the activation energy of the chemical reactions occuring inside the cell

Question 19

lesson 10

how heat has to be released from a cell

Answer 19

if heat were released abruptly in a cell it would cause a rise in temp that wou;d be fatal for the cell and organism –> to prevent this cellular reactions occur in multiple steps so energy is released gradually

Question 20

lesson 10

energy content

Answer 20

the amount of heat produced by the burning of 1 g of a substanced. measured in J/g

Question 21

calorimetry

Answer 21

• the chemical energy contained in food can be calculated through calorimetry
• in a calorimeter food is oxidized and the amount of energy (heat) thats released is measured

Ec= E nutrient / m

E nutrient = Ec x m

Ec = the energy content of a food (measured in KJ/g)
e nutrient = the amount of energy a nutrient provides (KJ)
m= mass of the nutrient (g)

Question 22

lesson 10

energy equivilant of food

Answer 22

carbohydrates: 17.2
proteins: 17.6
fat: 38.9
measured in KJ/g

Question 23

lesson 10

energy equivalent of oxygen

Answer 23

• Ee
• the amount of energy that can be produced in the body when 1L of oxygen is consumed
• if a nutrients combines w oxygen to produce energy, direct calorimetry can calculate how much energy is released by the combustion of a nutrient per unit of mass
• the amount of oxygen consumed in the process can also be measured

Question 24

energy equivilant of oxygen formula

Answer 24

Ee = E / V(02)

• Ee = energy equivilant of oxygen of a certain nutrient (Kj/L)
• E = amount of E obtained after a nutrient combustion (Kj)
• V(O2) = volume of consumed oxygen (L)

Question 25

# lesson 10d direct calometry for a person performing physical activity and formula

Answer 25

* the avg oxygen energy equivilant for a person = 20.2 KJ * so by measuring the amount of oxygen a person consums during physical exercise we can determine how much energy they have used Ee = E/V(O2) --> E = V(O2) x Ee

Question 26

# lesson 11 thermodynamic systems

Answer 26

* a part of the universe that is isolated for study * defined depending on the exhcanged of matter and energy w the environment that surrounds them: 1. open system 2. closed system 3. isolated system

Question 27

# lesson 11 open system thermodynamics

Answer 27

one that allows the exchange of mass and energy w the environment

Question 28

# lesson 11 closed system thermodynamics

Answer 28

one that exchanges energy but not mass

Question 29

# lesson 11 isolated system thermodynamic

Answer 29

one that exchanges neither matter nor energy

Question 30

# lesson 11 walls of a system

Answer 30

the surface that seperates the thermodynamics system from the surrounding environment

Question 31

# lesson 11 types of walls of a system

Answer 31

mobile walls: allow for a change of volume rigid/fixed walls: dont allow change of volume diathermic: allow heat exchange adiabotic: dont allow heat exchange permeable wall: allow the exchange of matter impermeable walls: dont allow exchange of matter

Question 32

# lesson 11 internal energy

Answer 32

* U * a state function thats the sum of the energies of all the particles in a system * during a transformation: bc internal energy is a state function there will also be a variation of internal energy --> the different in internal energy between state 2 (U2) and state 1 (U1) * formula: △U = U2 - U1

Question 33

# lesson 11 first principle of thermodynamics

Answer 33

* establishes the relationship between a thermodynamic transformation between heat and work w the variation of internal energy * another statement of the universal law of conservation of energy

Question 34

# lesson 11 variation of thermodynamics

Answer 34

* the variation of the internal energy of thermodynamic system is equal to the amount of heat the system receives minus the amount of work it performs * △U = Q - W Q > 0 : when system heats up Q < 0: when system looses energy W > 0 : when system performs work W < 0 : when work is done on system --> gas is compressed

Question 35

# lesson 11 1st principle applied to human metabolism

Answer 35

* human body = open system energy balance = energy inputs - energy losses △U = U nutrients - (Q-W) △U: variation of internal energy of human body U nutrients: internal energy provided by food Q: heat dissipated by the human body W: work done by the human body

Question 36

# lesson 11 2nd principle of thermodynamics

Answer 36

about how energy spreads out 1. energy tends to dissipate: energy moves from being concentrated to being spread out 2. Entropy (S) increases: entropy is a measure of disorder. In any process the total entropy of the universe always increases or stays the same (never decreases) --> △S = 0

Question 37

# lesson 11 entropy - symbol, def, during transformation

Answer 37

S a state function used to measure the degree of organization of the system during transformation there will be a variation of entropy △S which is the entropy diff between state 2 (S2) and state 1 (S1)

Question 38

# lesson 11 variation of entropy

Answer 38

* in an isothermal thermodynamic process, entropy variation is defined as the amount of heat per temperature, measured in kelvin * variation of entropy of a thermodynamic system: the part of the energy of the system that can't be used to perform work per unit of temp

Question 39

# lesson 11 historical statements of the 2nd principle of thermodynamics

Answer 39

* clausius statement: heat doesnt flow spontaneously from a cold body to a hot body * kelvins statement: its impossible to transform heat into work w 100% efficiency

Question 40

# lesson 11 Entropy and Disorder

Answer 40

Main Idea: Natural processes lead systems from order to disorder (higher entropy). Why? Because disordered configurations are statistically more probable. Implication: Entropy naturally increases; systems evolve toward disorder unless energy is added.

Question 41

# lesson 11 Order Requires Energy

Answer 41

Living Organisms: Though the second law says systems move toward disorder, organisms can temporarily maintain or create order. How? By inputting energy. Creating order (like organizing a cell or repairing tissue) isn’t spontaneous; it needs energy.

Question 42

# lesson 11 Entropy in Living Systems

Answer 42

Key Insight: Even when a cell maintains its internal order (reducing its entropy), the total entropy of the universe still increases. Example: A cell consumes nutrients (chemical energy), maintains structure, but releases heat — increasing environmental entropy. Conclusion: Organisms can decrease their own entropy only by increasing the entropy around them, complying with the second law.