Force meter
A force meter is an instrument to measure the magnitude of a force. This is often just a spring contained within a cylinder that has a scale to mark the extension of the spring produced by the force. In the International System of Units, the unit of force is the newton (symbol N). A force meter that measures force in newtons may be referred to as a newtonmeter.
Newton (unit)
Newton's second law of motion states that , where is the force applied, is the mass of the object receiving the force, and is the acceleration of the object. The newton is therefore:
where the following symbols are used for the units: N for newton, kg for kilogram, m for metre, and s for second.