|
3) Energy
It’s
defined as ‘the Capacity’ of doing work, such as lifting
a 10kg weight up to a height of 5 Meters and then ‘giving up’.
Or like a Tank full of a Car that can take you, say, 500km before it
needs to be filled up again. It’s measure, therefore, is ‘kg-meters’
or Watt-hours etc. A ‘KW/Kilo-Watt’ is simply = 1000 Watts.
4) Torque
While most of us can imagine that ‘Force’ is a ‘linear’
thing – like 2-people applying ‘X’ amount of force
to ‘push’ a Car weighing ‘Y’ kgs, when it comes
to ‘Torue’, most people find it difficult to comprehend
as to what it is.
In other words, it can be defined as the force required to ‘twist
or turn’ some thing, For example, like kicking down the starting
lever of a Mobike, which actually ‘rotates’ the Bike’s
engine to get it going. The measuring ‘Unit’ of such a ‘rotary-force’,
therefore, is ‘kg-meters’ or ‘Foot-Pounds’ as
its FPS equivalent (not to be confused with the unit of work).
Here, ‘kg’ is the ‘linear or tangential force’
applied to the kick pedal – say ‘F’ and ‘meter’
being the ‘radial length’ of the kick-starting lever –
say ‘R’. Therefore, the ‘torque’ applied in
this instance to the kick-pedal shaft, to rotate the engine, is ‘F
x R’ kg-meters.
Suffice to say that all ‘rotating’ machines like Engines/Elect.
Motors etc., essentially produce a ‘rotary force’ at their
'output shaft’. Since they also
‘rotate’ over a designed range of ‘speeds’ –
RPM in their case - they inevitably have a ‘Speed vs Torque Characteristic’
when the two variables/Torque and RPM are plotted on an X-Y axis.
Since by definition ‘Power’ is the ‘rate’ of
doing work, in case of a Rotating machine or an ICE, Power is simply
a straight ‘multiple’ of ‘torque’ and ‘rpm’
- at that particular ‘rpm’. It follows, therefore, that
the ‘shape’ of the ‘Power vs Rpm’ Curve of an
ICE is quite similar to that of its ‘mother’ Torque vs Rpm’
Curve.
Typical ‘Speed-Torque’ and ‘Speed-Bhp’ Characteristics
of an Internal Combustion Engine look like the ones below:
|
