# The Newton Meter

 Newton meters (or force meters) use Hooke's Law to measure force. A spring stretches proportionally to the force tugging at it. The construction of the meter stops you overstretching the spring - unless you really overload it!. Hold it vertically to weigh objects You must hold the meter vetically to weigh something with it. The best way to do that it to hang it up by its hook. It then automatically is positioned vertically in the Earth's gravitational field. Safety! Don't hold heavy objects over your foot... or anyone elses! If the newton meter breaks or the object comes loose it could really hurt you.

Zero errors

Before you add the weight to the meter you must check that it is reading zero.

If it is not it must be adjusted to correct the 'zero error', or a reading of that error should be taken and then taken into account when calculating the weights measured with it.

How accurate is it?

To check it is making accurate readings you could use it to weigh some standard weights. You should use weights across the range it is designed to measure (small medium and large for it!).

Estimate how accurately you can read it.

You can usually be sure of reading to the nearest half a division on the scale, but if the markings are very close together that can be to the nearerst division - not half a division.

Avoid parallax error

You should always make readings at eye level. When you look at a scale marker from an angle you get a wrong reading

Never just use a meter without checking it out first and thinking carefully about how you are going to use it!