A dynamometer is a device specially designed to measure the force exerted by some objects with respect to others. Today, we will see how to make a dynamometer using a spring and of course, the acceleration of gravity and the mass of different objects.
- A metre-long wooden strip.
- Graph paper.
- A spring with support.
- A small container as a support.
- Objects of known mass.
- A pencil.
- A wooden base.
- A couple of nails.
- A small plastic plate.
- Thin rope.
We take the long wooden strip and attach it with a nail to the base so that it is well fixed. Then, we place another nail in the upper part of the long wooden strip and we place there the spring.
At the bottom of the springIn the next step, we place a small plastic plate, helping us with a piece of thin string. This plastic plate will be used to place the objects we are going to measure. Along the long strip of wood, place a piece of graph paper and mark the place where the plate rests with a zero (0).
Calibration of the dynamometer
Once we have built our dynamometerWe proceed to calibrate it from our zero. To do this, we place objects of known mass (standard) on the plate. For example, an object with a mass of 10g and we mark up to where the plate went down on the dynamometer and place the mark as 10g. We repeat the operation with objects of 5g, 15g, 20g, or according to our taste, depending on the scale we use and the type of spring we have.
After marking the measurements of the standards, we are ready to make measurements with objects of unknown mass, interpolating between the values marked on the dynamometer previously, and we will obtain the mass and weight of the object to be measured.
How it works
The dynamometer which we have just constructed, uses the concept of Hook's Law of springs to measure force (weight is a force). This law tells us that the spring will stretch to a certain extent as a consequence of the force applied to it and according to its elastic limit. In our case, we will use gravity as acceleration. Recall that a force is the product of the mass and the acceleration experienced by a body.