Physical Units

iCALCULA offers the possibility of operate with both adimensional and physical quantities. During numeric input mode, you can access Unit menu through the |UNIT| key for selecting the proper physical magnitude that represents the input number. Unit menu shows a complete list of physical magnitudes expressed in the International System of Units. Each unit in the list has a right accessory icon that enters a sublist with multiples, submultiples and common non-SI units for that magnitude. When numbers in the stack have a unit defined, they are properly operated. The result will show consequent unit.

Out of numeric input mode, the |UNIT| key enters Unit Conversion menu. SI Unit list is limited to magnitudes with the same physical dimension as x-register. Right accessory icon enters the sublist with corresponding multiples, submultiples and non-SI units. Once you select one unit, x-register magnitude is converted and expressed in the selected unit.

Unit list contains a first item called "Last used units" that collect the units you have used in the past so that you can recall them more easily.

When operating with magnitudes, you don't need to make conversions. iCALCULA make that work for you and applies the appropriate restrictions. For example, if you calculate:

2 meters + 1 centimeter

|2|   |UNIT|   |Length Units|   |ENTER|   |1|   |UNIT|   |Length Units  ⓘ|   |cm|   |+|

2.01 m

You obtain 2.01 meters. iCALCULA gives the result in the unit of first operand (y-register).

Let's operate a more complex expression. We'll calculate the force necessary to accelerate 2 grams at 3 m/s²:

F = m a = 2 grams x 3 m/s²

|2|   |UNIT|   |Mass Units ⓘ|   |g|   |ENTER|   |3|   |UNIT|   |Acceleration Units|   |×|

0.006 N

Result is written in Newtons because it is the SI unit for the magnitude Force. You can then use Unit menu if you want to express the result in other unit. When you press |UNIT| key you obtain a one row list: Force Units. If you press the right accessory icon and choose |pond| key, result now appears in x-register as:

0.61183 pond

If we calculate the work of such a force acting on a system over 2 meters,

W = F D = 0.61183 pond * 2 m

|2|   |UNIT|   |Length Units|   |×| kg

0.012 N m

If you press |UNIT| key you obtain a tow row unit list: Moment of Force Units and Energy-Work-Amount of Heat Units. The reason is that both magnitudes are equal dimensionally.

When you are operating with magnitudes some intermediate results may be have no dimensional correspondence with a defined magnitude. In such case its dimension will be expressed through powers of fundamental units. For example, if we calculate the square of previous result:

|x²|

0.000144 m[4]kg[2]s[-4]

which indicates that the dimension is m⁴ kg² / s⁴.