Understanding US Therms to Ergs Conversion
The US therm (thm) is a natural-gas energy unit equal to 100,000 BTU, used for utility billing. The erg is the unit of energy in the centimeter-gram-second (CGS) system, equal to 10⁻⁷ joule, or the work done by a force of one dyne over one centimeter. Converting therms to ergs restates a large practical heating unit in the small CGS unit still seen in some physics and astronomy contexts, yielding a very large number.
Conversion Formula
To convert US Therms to Ergs, multiply by this factor:
Step-by-Step Example
Convert 25 US Therms to Ergs.
How to Convert US Therms to Ergs
Restate a gas therm in CGS ergs with one multiplication.
- Note the value: Record the energy amount in US therms.
- Multiply by the factor: Multiply by 1.054804 × 10¹⁵ ergs per therm.
- Use scientific notation: The result is very large, so express it in exponential form.
- Worked result: 25 therms × 1.054804 × 10¹⁵ = 2.63701 × 10¹⁶ ergs.
US Therms to Ergs conversion table
| US Therms (thm) | Ergs (erg) |
|---|---|
| 0 | 0 |
| 1 | 1054804000000000 |
| 2 | 2109608000000000 |
| 3 | 3164412000000000 |
| 4 | 4219216000000000 |
| 5 | 5274020000000000 |
| 6 | 6328824000000000 |
| 7 | 7383628000000000 |
| 8 | 8438432000000000 |
| 9 | 9493236000000000 |
| 10 | 10548040000000000 |
| 15 | 15822060000000000 |
| 20 | 21096080000000000 |
| 25 | 26370100000000000 |
| 30 | 31644120000000000 |
| 40 | 42192160000000000 |
| 50 | 52740200000000000 |
| 60 | 63288240000000000 |
| 70 | 73836280000000000 |
| 80 | 84384320000000000 |
| 90 | 94932360000000000 |
| 100 | 105480400000000000 |
| 150 | 158220600000000000 |
| 200 | 210960800000000000 |
| 250 | 263701000000000000 |
| 300 | 316441200000000000 |
| 400 | 421921600000000000 |
| 500 | 527402000000000000 |
| 600 | 632882400000000000 |
| 700 | 738362800000000000 |
| 800 | 843843200000000000 |
| 900 | 949323600000000000 |
| 1000 | 1054804000000000000 |
| 2000 | 2109608000000000000 |
| 3000 | 3164412000000000000 |
| 4000 | 4219216000000000000 |
| 5000 | 5274020000000000000 |
| 10000 | 10548040000000000000 |
| 25000 | 26370100000000000000 |
| 50000 | 52740200000000000000 |
| 100000 | 105480400000000000000 |
| 250000 | 263701000000000000000 |
| 500000 | 527402000000000000000 |
| 1000000 | 1.054804e+21 |
What is the US Therm?
The US therm is a unit of heat energy used primarily in the natural gas industry to measure and bill the energy content of gas supplied to homes and businesses in the United States.
Definition
The US therm is defined as 100,000 British thermal units (BTU) based on the 59 °F (15 °C) BTU:
More precisely, the US therm equals exactly 105,480,400 joules (about 105.48 MJ). It should not be confused with the slightly larger UK therm, which is based on the International Table BTU and equals 105,505,585.257 J.
Origin and History
The therm entered use in the 20th century as gas utilities shifted from billing customers by volume to billing by delivered energy, since the heating value of natural gas varies with its composition. Combining "therm" (from the Greek thermē, heat) with a fixed BTU count gave a convenient billing unit roughly equal to the energy in 100 cubic feet of typical natural gas.
Law and Notable Facts
In the United States the therm is a legally recognized commercial unit for natural gas sales. Gas meters record volume in hundreds of cubic feet (ccf), which utilities multiply by a "therm factor" reflecting the gas's actual heat content to convert to therms for billing.
Real-World Examples and Conversions
- A typical US home uses roughly 500 to 1,000 therms of natural gas per year for heating, cooking, and hot water.
- 1 therm equals about 29.3 kilowatt-hours of energy.
- Burning 1 therm of natural gas releases approximately 105.5 MJ of heat, enough to run a 20 kW furnace at full output for about 88 minutes.
What is the Erg?
The erg is a unit of energy in the centimetre-gram-second (CGS) system, historically common in physics, astronomy, and mechanics before the SI joule became standard.
Definition
One erg is the work done by a force of one dyne acting over a distance of one centimetre:
This equals exactly one ten-millionth of a joule (10⁻⁷ J), or equivalently 1 g·cm²/s². The erg is a small unit, reflecting the small base units of the CGS system.
Origin and History
The name comes from the Greek ergon, meaning "work." The unit was formally adopted by the British Association for the Advancement of Science in 1873 as part of the CGS system and remained the dominant energy unit in physics literature well into the 20th century.
Law and Notable Facts
The erg has been largely superseded by the joule and is deprecated in the modern SI framework, but it persists in astrophysics, where luminosities and energies are still frequently quoted in ergs and erg per second.
Real-World Examples and Conversions
- 1 joule equals 10 million ergs.
- A mosquito in flight expends energy on the order of a few ergs per wingbeat.
- The Sun radiates about 3.8 × 10³³ ergs every second, equivalent to 3.8 × 10²⁶ watts.
Frequently Asked Questions
How many ergs are in one US therm?
One US therm equals about 1.054804 × 10¹⁵ ergs, because an erg is only 10⁻⁷ joule.
How do I convert US therms to ergs?
Multiply the therm value by 1.054804 × 10¹⁵ and keep the answer in scientific notation.
How many therms equal one erg?
One erg is about 9.480434 × 10⁻¹⁶ US therms, a tiny fraction.
What is an erg?
The erg is the CGS unit of energy, equal to 10⁻⁷ joule, historically used in physics and still referenced in astrophysics.
Why is the erg count so large?
Because an erg is very small (10⁻⁷ joule) and a therm is about 10⁸ joules, a single therm contains on the order of 10¹⁵ ergs.
People also convert
Complete US Therms conversion table
| Unit | Result |
|---|---|
| Watt-seconds (Ws) | 105480400 Ws |
| Watt-minutes (Wm) | 1758007 Wm |
| Watt-hours (Wh) | 29300.11 Wh |
| Milliwatt-hours (mWh) | 29300110 mWh |
| Kilowatt-hours (kWh) | 29.30011 kWh |
| Megawatt-hours (MWh) | 0.02930011 MWh |
| Gigawatt-hours (GWh) | 0.00002930011 GWh |
| Joules (J) | 105480400 J |
| Kilojoules (kJ) | 105480.4 kJ |
| Megajoules (MJ) | 105.4804 MJ |
| Gigajoules (GJ) | 0.1054804 GJ |
| British Thermal Units (IT) (BTU) | 99976.13 BTU |
| Electronvolts (eV) | 6.583569e+26 eV |
| Ergs (erg) | 1054804000000000 erg |
| Foot-pounds (ft-lbf) | 77798350 ft-lbf |
| Tonnes of TNT (t-tnt) | 0.02521042 t-tnt |
| calories (cal) | 25210420 cal |
| Kilocalories (kcal) | 25210.42 kcal |