Understanding the Forces: A Look at Three Essential Laws in Physics

Physics can often seem quite a dry and abstract subject. Consequently, for many people, it can be intimidating. So much so, in fact, that you might not give it much thought once you’ve graduated high school.

With that said, there are a number of basic physical principles worth remembering. These can open up creating pursuits, from electronics and circuit design to architecture. Understanding them can also help you to feel more comfortable with the basic concepts in physics, which might encourage you to delve deeper – and perhaps even become passionate about the subject!

Ohm’s Law: V = I × R

Among the first basic principles that new electronic engineers come across is Ohm’s law. Through this law, you’ll be able to work out exactly what value resistor to shop for in order to supply the desired current to a given point in your circuit. If you’re lighting up an LED for the first time using the five-volt rail from a USB supply, then you might choose a value of, say, 220 ohms. But using Ohm’s law, you can determine exactly what you need.

Ohm’s law states that voltage (in volts) equals current (in amps) times resistance (in ohms). You can rearrange this formula to achieve any result you like. If you know that the voltage is fixed at five volts, for example, and you need a current of 40 milliamps, then you’ll need a 120-ohm resistor – since five volts divided by 0.04 amps is 125!

This law is used not just in circuit design, but in power distribution, testing, and troubleshooting. If you can work out in a few seconds what the current at a given point should be, based on the resistor values, then you’ll have an easier time diagnosing problems in a given circuit. All you need is a multimeter, or perhaps a selection of digital voltmeters.

Law of Inertia

Among the most famous physical laws is Newton’s first law of motion, which holds that an object at rest, or moving in a straight line, will maintain its speed and direction unless it’s acted on by an external force. This force could be anything, including air resistance and friction, as well as other objects. Fire a cannon in the vacuum of space, and you can assume that the projectile will keep traveling forever until it collides with something.

Newton’s first law is applied in vehicle design, and especially in safety. If a vehicle comes to a sudden halt, the passengers will continue moving forward until they’re stopped. This is the law of inertia in action.

If you’re planning a space mission, the law is similarly crucial. It will allow you to work out exactly how much fuel you’ll need. Once a spacecraft has achieved the desired trajectory, it will continue traveling until the fuel is needed to bring it to a halt.

If those examples sound overly technical, then why not think about sports? The laws of physics apply in the worlds of football and baseball, too. They can be used to work out exactly how much force is going through a given joint when a player suddenly changes direction!

Law of Universal Gravitation

The second of Isaac Newton’s laws of motion claims that every mass in the universe attracts every other mass. The force of the attraction is proportional to the product of their masses, and inversely proportional to the square of the distance between them. In other words, objects gravitate toward one another when they’re close together, but this force drops off quickly as distance goes up.

Through this, we can establish exactly how close we need to be to a planet to stay in orbit around it. We might also use it to work out when high tide will be, and exactly how high it will be, which is information that the fishing industry can’t do without.