Chapter 4 Physics

Question 1

Thermodynamics

Answer 1

the field of physics that deals with forces and motion involving the transfer of thermal energy

Question 2

First Law of Thermodynamics

Answer 2

Energy cannot be created nor destroyed but can be transformed from one form to another or transferred from one object to another

Question 3

Second Law of Thermodynamics

Answer 3

No process is 100% efficient in converting energy into work (some energy will always be converted to thermal energy due to friction)

Question 4

Thermal energy always flows from object at a ______ temperature to objects at a ______ temperature

Answer 4

higher, lower

Question 5

Empedocles

Answer 5

all matter consists of four elements; earth, air, fire, and water (when objects burn fire is released)

Question 6

Phlogiston

Answer 6

substances that could burn contained an invisible fluid called “phlogiston” (flowed out of objects when burned)

Question 7

Caloric Theory

Answer 7

•“Caloric” was thought to be a massless fluid found in all matter
•It cannot be created not destroyed but can flow from warmer objects to cooler objects
•The term “calorie” is still used today (1 cal. Increases temperature of 1g of water by 1 degree

Question 8

The Count Rumford Hypothesis

Answer 8

•Notice cannon barrels get hot
•Mechanical energy can be converted to heat = heat is equivalent to energy

Question 9

Julius Robert Mayer

Answer 9

•Found evidence supporting Rumford
•Recognized the body uses oxygen to break down food and use it for energy

Question 10

James Prescott Joules

Answer 10

Discovered that mechanical energy is equivalent to heat (unit of energy = Joule)

Question 11

Kinetic Molecular Theory

Answer 11

•Atoms are in random motion and collide with each other, transferring energy and doing work
•Work and energy are related, both measured in Joules

Question 12

Kinetic Energy

Answer 12

the energy of motion

Question 13

Kinetic-molecular energy

Answer 13

energy of atoms and molecules in constant random motion (thermal energy)

Question 14

Heat

Answer 14

the transfer of thermal energy from one object to another

Question 15

Temperature

Answer 15

Average kinetic energy of the atoms or molecules in a substance

Question 16

Specific Heat Capacity

Answer 16

the amount of energy (J) to increase the temperature of 1g of the substance by 1 degree (Unit: J/g°C)

Question 17

Specific Heat Capacity of Water

Answer 17

•Water molecules form strong hydrogen bonds with each other
•Lots of kinetic energy is needed for water molecules to break away from each other

Question 18

Specific Heat Capacity Formula

Answer 18

Q=mcΔT

Question 19

Heat of Fusion

Answer 19

Q= nHfus (energy needed to melt or freeze a substance)

Question 20

Heat of Vaporization

Answer 20

Q= nHvap (energy needed to vaporize or condense a substance)

Question 21

Physics of Work

Answer 21

•Work is done when a force acting on an object changes the position or condition of the object
•Work is the transfer of mechanical energy from one object to another
•Measured in Joules, which are equivalent to Nm

Question 22

Calculating Work

Answer 22

W= fΔd

Question 23

Negative Work

Answer 23

when force is applied in the opposite direction of the motion

Question 24

Position vs. Force Graphs

Answer 24

•Show the relationship between Force and change in position
•Length is the force
•Width is the distance
•Rectangle: A= l • W
•Triangle: A= 1/2 b • h
•Non-uniform shapes: calculated by finding the area of one square on the grid then multiplying it by the number of squares

Question 25

Interal Combustion Engines

Answer 25

1. The fuel goes directly into the cylinder (intake stroke) (intake valve opens)
2. Combustion occurs inside the cylinder (compression stroke) (both intake and exhust valves close)
3. The hot gases expand and push the piston down the cylinder (power stroke) (both valves are still closed)
4. When the pressure and/or volume of a gas increases, the gas does work (exhust stroke) (exhust valve opens)

Question 26

Steam Engines

Answer 26

“external combustion engines”, fuel is burned outside the engine and is used to generate steam in a boiler (steam drives the pistons)

Question 27

Production of Electrical Energy

Answer 27

thermo-electric generating stations first produce heat, which used to convert water into steam in large boilers. The steam turns turbines connected to larger generators