A Newton spring balance
Professor Mac is using a Newton spring balance in his experiments to illustrate Newton’s second law of motion.
Do you know what it is? Well it is shown below. The balance contains a spring which provides a measure of the force applied to the balance. The larger the force, the more the spring extends, with the force level indicated by the scale on the balance.
The Newton Spring Balance and Hooke’s Law
The Newton spring balance uses a law known as Hooke’s Law to relate the spring extension to the force being measured. There is a direct relationship between how much the spring extends and the force required to extend it.
If we place a weight at the end of the spring there is a force applied to the spring due to the weight. Hooke’s law says that the spring will then extend. As it extends you can measure the force due to the weight by looking at the scale. In the picture below you can see Professor Mac applying a force to the end of the spring using his hand. The spring extension and force applied is indicated on the scale.
Before you go!
So do you know how to determine how much a spring extends when a force is applied to it? We need to know this if we are going to use it to measure the force.
This is done through a process of applying various forces to it and measuring the amount it extends for each unit of force. This enables us to calibrate it and create a scale which indicates force. Professor Mac shows you how to do this in his video on Hooke’s Law.