Basic Physics for Radiography

Question 1

what is velocity?

Answer 1

rate of change of position over time

Question 2

formula for velocity

Answer 2

v = d/t

Question 3

what is acceleration?

Answer 3

rate of change of velocity over time

Question 4

what are the four fundamental forces in nature (from weakest to strongest)

Answer 4

gravity
weak nuclear force - important in radioactive decay
electromagnetism
strong nuclear force - holds atom together

Question 5

what is force?

Answer 5

some action that changes the motion of an object
can be physical or invisible force

Question 6

formula for force

Answer 6

f = m x a

Question 7

what are the units for force?

Answer 7

Newtons (N)

Question 8

newtons first law

Answer 8

body remain at rest or continue to move with constant velocity in a straight line unless acted on by an external force

Question 9

newtons second law

Answer 9

the force that acts on an object is equal to the mass of the object multiplied by acceleration produced

Question 10

newtons third law

Answer 10

for every action there is an equal and opposite reaction

Question 11

what does friction do?

Answer 11

it is a force that slows acceleration down

Question 12

what is weight?

Answer 12

force on an object from the force of gravity

Question 13

what speed do objects fall to earth at?

Answer 13

Objects that fall to earth accelerate at a constant rate of 9.8m/s2

Question 14

what are the units of weight?

Answer 14

Newtons (N)

Question 15

what are the units of mass?

Answer 15

kg

Question 16

what is work?

Answer 16

the force applied to an object multiplied by the distance its applied

Question 17

formula for work

Answer 17

work = force x distance

Question 18

what is energy?

Answer 18

the ability to do work

Question 19

what is the unit of energy?

Answer 19

joule

Question 20

what is a joule?

Answer 20

the work/energy required to move an object with the force of one Newton over a distance of one meter

Question 21

what is power?

Answer 21

the rate of doing work

Question 22

formula for power

Answer 22

power = work / time

Question 23

what are the units of power?

Answer 23

watt (W)

Question 24

what is a watt the same as?

Answer 24

joule/second

Question 25

what are some forms of energy

Answer 25

gravitational potential energy kinetic energy mechanical energy chemical energy electrical energy thermal energy electromagnetic energy nuclear energy

Question 26

what is gravitational potential energy?

Answer 26

ability to do work because of height lifting an object to a greater height gives them more potential energy

Question 27

formula for gravitational potential energy

Answer 27

PE = m x g x h m is mass (kg), g is gravity (=9.8ms2), h is height

Question 28

what is kinetic energy?

Answer 28

energy of motion

Question 29

formula for kinetic energy

Answer 29

KE = 1/2 mv2 m is mass, v is velocity

Question 30

what is mechanical energy?

Answer 30

e.g. sound

Question 31

what is chemical energy?

Answer 31

energy released by a chemical reaction

Question 32

what is electrical energy?

Answer 32

work that can be done when an electron moves through an electric potential difference (voltage)

Question 33

what is thermal energy?

Answer 33

Kinetic energy of molecules Faster the molecules vibrate, more thermal energy a substance has and the higher its temp

Question 34

what is nuclear energy?

Answer 34

energy contained in the nucleus of an atom

Question 35

what does conservation of energy mean?

Answer 35

energy cannot be created or destroyed but can be transferred from one form to another

Question 36

what is a transducer?

Answer 36

designed to change one form of energy into a different form

Question 37

what should the sum of kinetic and potential energy be?

Answer 37

the same E = PE + KE

Question 38

what is the unit of heat?

Answer 38

calorie

Question 39

what is a calorie?

Answer 39

heat required to raise the temperature of 1g of water by 1 degree C

Question 40

what is temperature calibrated at?

Answer 40

Celsius Fahrenheit Kelvin

Question 41

what is the lowest possible temperature?

Answer 41

absolute zero = zero degrees Kelvin = -273 degrees C

Question 42

three ways to get rid of heat in an xray tube?

Answer 42

1. convection 2. conduction 3. radiation

Question 43

what is convection?

Answer 43

hot molecules in a gas or liquid physically mix from one place to another

Question 44

how does convection work?

Answer 44

Molecules with more kinetic energy collide with those with less kinetic energy, this distributes kinetic energy evenly amongst the molecules Temp of hot substance drops, temp of cold substance rises until their temps are the same

Question 45

what is conduction?

Answer 45

transfer of heat through a material (objects need to be in contact) Hotter molecules bump into cooler molecules making them vibrate and it travels along - transfer of kinetic energy by collisions between atoms

Question 46

what does conduction result in?

Answer 46

equal temps of the two objects

Question 47

how does rate of conduction increase?

Answer 47

with the area of the object the ability of the object to conduct heat temperature difference between the two materials

Question 48

what is thermal radiation?

Answer 48

transfer of heat by emission of infrared radiation

Question 49

how do x-ray tubes primarily cool?

Answer 49

by radiation

Question 50

how does conduction work in an x-ray tube?

Answer 50

down anode shank from glass of x-ray tube to surrounding oil

Question 51

how does convection work in an x-ray tube?

Answer 51

Surrounded by oil. Heat carried away by convection as heated oil is stirred and mixed with cool oil

Question 52

how does radiation work in an x-ray tube?

Answer 52

release mainly light, IR, UV rays, some x-rays too most absorbed by tube housing

Question 53

what does Amps measure?

Answer 53

flow of electrons

Question 54

SID meaning

Answer 54

source to image distance

Question 55

what is the standard distance for an x-ray?

Answer 55

1m