si units and horse power
DESCRIPTION
SI Units and Horse Power DefinitionTRANSCRIPT
Lecture – 12.08.2014
By
P. Kanthasamy
Principal Technical Officer
Environmental Technology Division
CSIR- Central Leather Research Institute
Adyar, Chennai-600 020
Email:[email protected] Mobile:9445587722
Definitions of UNITS
• Joules
• Calories
• Btu
• Horse power
• Conversion of Centigrade to Fahrenheit and vice versa
• Ton ( TR-Ton Rating)
• Prefix for Power in Watts
SI UnitsQuantity SI-unit Alternative unitsTime s (second) h (hour)
Length m (meter) in (inch)
ft (foot)
Mass kg (kilogram) lb (pound)
Temperature K (Kelvin) °C (Celsius)
°F (Fahrenheit)
Force N (Newton) kp (kilopond)
Pressure Pa (Pascal) = N/m2 bar
atm (atmosphere)
mm Hg (millimeter mercury column)
psi (pound per square inch)
Energy J (Joule) = Nm kWh (kilowatt hour)
cal (calorie)
Btu (British thermal unit)
Power W (Watt) = J/s calorie/h, Btu/h
Pound conversion• 1Kg=2.2046 pounds
• 1pound=.04536 kg
• 1pound= 16 ounce
• 1 ounce= 29.5735ml=28.3495 gms
• 1 cubic meter is equal to 33814.0225589 oz, or 1000000 ml.
• 1 Cubic metre=1000litres
• The number of fluid ounces which equal a pound depend on the type of liquid being measured.
• Liquids have different densities, a factor which affects how much the fluid weighs. For example, sixteen fluid ounces of water weighs 1.043 pounds and one fluid ounce of milk weighs 1/16th of a pound.
• Pounds are a measuring unit used to measure weight and fluid ounces are a unit used to measure volume. The fluid ounce is used in the imperial measuring system.
What is a Joule ?
• 1 Joule = 1Nm
• Joule is SI unit of work or energy, equal to the work done by a force of one newton when its point of application moves one metre in the direction of action of the force, equivalent to one 3600th of a watt-hour.
1 N
1m
1 N
Joule –Cont.
• One joule per second equals 1 wattor
• 0.737 foot pounds, or
• 9.47 x 10^-4 British thermal units (Btu) (one Btu equals about 1,055 joules).
• It equals about 0.24 calories, or roughly the energy required to raise a spoonful of food to mouth.
• Named after UK physicist James Prescott Joule (1818-89) who in 1843 discovered the mechanicalequivalent of heat.
One Calorie1kcal =4.187 kJoules
Calorie
• One Calorie is the amount of heat required to raise the temperature of one gram of water by 1°C.
• It equals 4.18 joules or about 0.004British thermal units (Btu). Also called gram calorie or small calorie.
• Unit of energy-producing potential of food (commonly shown as calorie on the nutrition label of the item) is actually a kilocalorie equal to 1,000 small calories amount of heat required to raise the temperature of one kilogram of water by 1°C.
• It equals 4.18 kilojoules or about 4 British thermal units (Btus). Also called food calorie, kilogram calorie, large calorie, or nutrition calorie.
British Thermal Unit (Btu)
• A BTU (British Thermal Unit) is the amount of heat necessary to raise one pound of water by 1 degree Farenheit (F).1 British Thermal Unit (BTU) = 1055 J (The Mechanical Equivalent of Heat Relation)1 BTU = 252 cal = 1.055 kJ1 Quad = 1015 BTU (World energy usage is about 300 Quads/year, US is about 100 Quads/year in 1996.)1 therm = 100,000 BTU1,000 kWh = 3.41 million BTUPower Conversion
• 1 horsepower (hp) = 745.7 watts
Btu –contd.
• This is the standard measurement used to state the amount of energy that a fuel has as well as the amount of output of any heat generating device.
• You might be able to imagine it this way. Take one gallon (8 pounds) of water and put it on your stove. If the water is 60 degrees F and you want to bring it to a boil (212 degrees F.) then you will need about 1,200 BTUs to do this.
Btu-contd.• One 1Btu= 252 small calories or 0.252 kilocalories,
• 1 Btu=778.17 foot pounds, or 1055.06 joules.
• 1 kWh=3412 BTUs
• One pound of air-dried wood generates about 7,000 Btu,
• a gallon of liquid propane (a hydrocarbon) about 92,000 Btu,
One Gallon=3.78541 (US gallon)
• a gallon of fuel-oil about 140,000 Btu, one barrel of gasoline about 5.25 million Btus,
• One barrel= 159 litres approximately=42 Gallons
• an average ton of coal about 20 million Btu
• one kilowatt-hour of electricity about 3,400 Btu.Used also as a unit of measurement for natural gas prices (1,034 Btu = 1 cubic-foot of natural gas).
• One Btu per hour equals 0.293 watt and is represented by the symbol Btu/h (not Btuh).
Btu –contd.
• MBTU stands for one million BTUs, which can also be expressed as one decatherm (10 therms). MBTU is occasionally used as a standard unit of measurement for natural gas and provides a convenient basis for comparing the energy content of various grades of natural gas and other fuels.
• One cubic foot of natural gas produces approximately 1,000 BTUs, so 1,000 cu.ft. of gas is comparable to 1 MBTU. MBTU is occasionally expressed as MMBTU, which is intended to represent a thousand thousandBTUs.
Power
• Power is defined as the rate at which work is done upon an object.
• Like all rate quantities, power is a time-based quantity. Power is related to how fast a job is done. Two identical jobs or tasks can be done at different rates - one slowly or and one rapidly. The work is the same in each case (since they are identical jobs) but the power is different. The equation for power shows the importance of time:
• Power = Work / time
• P = W / t
What is horsepower?
The story goes that Watt was working with ponies lifting coal at a coal mine, and he wanted a way to talk about the power available from one of these animals.
He found that, on average, a mine pony could do 22,000 foot-pounds of work in a minute.
He then increased that number by 50 percent and pegged the measurement of horsepower at 33,000 foot-pounds of work in one minute.
Horse Power What horsepower means is this: In Watt's judgement, • one horse can do 33,000 foot-pounds of work every
minute. So, imagine a horse raising coal out of a coal mine as shown above.
• A horse exerting 1 horsepower can raise 330 pounds of coal 100 feet in a minute,
• or 33 pounds of coal 1,000 feet in one minute, • or 1,000 pounds 33 feet in one minute.
You can make up whatever combination of feet and pounds you like. As long as the product is 33,000 foot-pounds in one minute, you have a horsepower.
Conversion of HorsepowerHorsepower can be converted into other units as well. For example:
• 1 horsepower is equivalent to 746 watts. So if you took a 1-horsepower horse and put it on a treadmill, it could operate a generator producing a continuous 746 watts.
• 1 horsepower (over the course of an hour) is equivalent to 2,545 BTU (British thermal units).
• If you took that 746 watts and ran it through an electric heater for an hour, it would produce 2,545 BTU
• One BTU is equal to 1,055 joules, or 252 gram-calories or 0.252 food Calories. Presumably, a horse producing 1 horsepower would burn 641 Calories in one hour if it were 100-percent efficient.
Prefix for Power in Watts
SI multiples for watt (W)
Submultiples Multiples
Value Symbol Name Value Symbol Name
10−1
W dW deciwatt 101
W daW decawatt
10−2
W cW centiwatt 102
W hW hectowatt
10−3
W mW milliwatt 103
W kW kilowatt
10−6
W µW microwatt 106
W MW megawatt
10−9
W nW nanowatt 109
W GW gigawatt
10−12
W pW picowatt 1012
W TW terawatt
10−15
W fW femtowatt 1015
W PW petawatt
10−18
W aW attowatt 1018
W EW exawatt
10−21
W zW zeptowatt 1021
W ZW zettawatt
10−24
W yW yoctowatt 1024
W YW yottawatt
Common multiples are in bold face
Conversion of Centigrade to Fahrenheit and vice versa
• Degree Fahrenheit = (1.8xDegree centigrade)+32
• 1degree Centigrade = (Fahreheit-32)/1.8
30degree centigrade is how many Fahrenheit?
Fahrenheit = (30 x 1.8 ) +32= 86 Degree
100 Degree Fahrenheit is how many deg. Centigrade?
Centigrade= (100-32)/1.8=37.7778
1 Ton Rating AC
• A Ton of refrigeration (RT) is a unit of power used to describe the heat-extraction capacity of air conditioning and refrigeration equipments.
• It is defined as the heat of fusion absorbed by melting 1 short ton of pure ice at 0 °C (32 °F) in 24 hours.
• 1Ton=1000kCals=4127kilojoules-12000 Btu/hr
Conversion of Units • How many kW and HP are there in 1 Ton?
• 1 Ton = 3.5168525 kW = 4.714Hp
• Explanation
• 1 Ton = 12,000 BTU/h1 Watt = 3.412141633 BTU/h
• 1 Ton = 12,000 / 3.412141633 = 3,516.8528 Watts =3.5168528 kW.
• 1 Ton = 3,516.8528 Watts = 3.516 kW.
• Also
• 1 Ton = 3,516.8528W / 746 = 4.7142798928 Hp →→→
(1 Hp = 746 Watts)
• 1 Ton = 4.714 Hp
1 Ton AC
• Quantity of heat is termed in Tons means if an air conditioner is able to remove 1000 kilocalories of heat
or 4120 kilojoules or 12000 BTU of heat in an hour that AC rated as 1Ton of AC
because 1000 Kilocalories or 4120 kilojoules or 12000 BTU equal to one Ton of heat.
• 1Ton Ac= Removing heat at the rate of 12000 Btu/hr
• if you have a ton of ice, it takes (143 BTU/lb) x (2000 lbs) = 286,000 BTUs to melt it completely in 24 hrs.
=286000Btu/24hrs=11916.66667=11917 Btu/hr
Hyundai i10 Engine
• Fuel type : Gasoline• Displacement : 1,086 cc• Max. Power : 69 ps / 5,500 rpm• PS stands for pferdestarke. • Most common car power is measured in PS & BHP(break horse
power)...BHP & PS are two measures adopted by two different standard agencies.
• 1BHP=.986PS• & 1BHP=745watts
• Max. Torque : 10.1 kg·m / 4,500 rpm•
• The i10 has three engines to choose from, a 1.1ℓ with 69 ps, the 1.25ℓ with 87 ps, and the 1.0ℓ with 69 ps.
• Constantly Variable Valve Technology (CVVT), which measures every drop of fuel for maximum efficiency is available on the 1.25. These engines not only deliver exceptional fuel economy, they give really low emissions.
Summary of Units• Energy Units and Conversions• 1 Joule (J) is the energy, equal to the force of one Newton acting through
one meter.•
1 Watt is the power of a Joule of energy per second•
Power = Current x Voltage (P = I V)•
1 Watt is the power from a current of 1 Ampere flowing through 1 Volt.
• 1 kilowatt is a thousand Watts.1 kilowatt-hour is the energy of one kilowatt power flowing for one hour.
(E = P t).1 kilowatt-hour (kWh) = 3.6 x 106 J = 3.6 million Joules• 1 calorie of heat is the amount needed to raise 1 gram of water 1 degree
Centigrade.1 calorie (cal) = 4.184 J(The Calories in food ratings are actually kilocalories.)
Problems1. When doing a chin-up, a physics student lifts her 42.0-kg body a distance of
0.25 meters in 2 seconds. What is the power delivered by the student's biceps?
2. Your household's monthly electric bill is often expressed in kilowatt-hours. One kilowatt-hour is the amount of energy delivered by the flow of 1 kilowatt of electricity for one hour. Use conversion factors to show how many joules of energy you get when you buy 1 kilowatt-hour of electricity.
3. An escalator is used to move 20 passengers every minute from the first floor of a department store to the second. The second floor is located 5.20 meters above the first floor. The average passenger's mass is 54.9 kg. Determine the power requirement of the escalator in order to move this number of passengers in this amount of time.
Answer for Question.1
• To raise her body upward at a constant speed, the student must apply a force which is equal to her weight (m•g). The work done to lift her body is
• W = F * d = (411.6 N) * (0.250 m)W = 102.9 J
• The power is the work/time ratio which is (102.9 J) / (2 seconds) = 51.5 Watts (rounded)
Q. An escalator is used to move 20 passengers every minute from the first floor of a department store to the second. The second floor is located 5.20 meters above the first floor. The average passenger's mass is 54.9 kg. Determine the power requirement of the escalator in order to move this number of passengers in this amount of time.Question 3
Answer:A good strategy would involve determining the work required to elevate one average passenger. Then multiply this value by 20 to determine the total work for elevating 20 passengers. Finally, the power can be determined by dividing this total work value by the time required to do the work. The solution goes as follows:W1 passenger = F • d • cos(0 deg)
W1 passenger = (54.9 kg • 9.8 m/s2) • 5.20 m = 2798 J (rounded)
W20 passengers = 55954 J (rounded)
P = W20 passengers / time = (55954 J) / (60 s)
P = 933 W
Question No.2Your household's monthly electric bill is often expressed in kilowatt-hours. One kilowatt-hour is the amount of energy delivered by the flow of 1 kilowatt of electricity for one hour. Use conversion factors to show how many joules of energy you get when you buy 1 kilowatt-hour of electricity.
Answer:• Using conversion factors, it can be shown that
• 1 kilo-watt*hour is equivalent to 3.6 x 106 Joules.
• First, convert 1 kW-hr to 1000 Watt-hours.
• Then convert 1000 Watt-hours to 3.6 x 106 Watt-seconds. Since a Watt-second is equivalent to a Joule.
Thank You
New Things to learn
• CD- Compact Disc
• DVD-Digital -Digital Versatile Disc
• USB- Universal Serial Bus
Definition of USB
• Universal Serial Bus (USB)
• Abbreviated as USB, Universal Serial Bus is a standard type of connection for many different kinds of devices.
Tip: The male connector on the cable or flash drive is typically called the plug. The female connector on the device, computer, or extension cable is typically called the receptacle.
receptacle
USB Version• There have been three major USB standards, 3.0 being the
newest:• USB 3.0: Called SuperSpeed USB, USB 3.0 compliant hardware
can reach a maximum transmission rate of 5 Gbps (5,120 Mbps).
• A planned update to the USB 3.0 standard will increase the maximum data rate to 10 Gbps (10,240 Mbps), matching that of Thunderbolt, a potential replacement for USB.
• USB 2.0: Called High-Speed USB, USB 2.0 compliant devices can reach a maximum transmission rate of 480 Mbps.
• USB 1.1: Called Full Speed USB, USB 1.1 devices can reach a maximum transmission rate of 12 Mbps.
• Most USB devices and cables today adhere to USB 2.0, and a growing number to USB 3.0.