Lesson 4: Applications of Newton's Laws

So far, through our lessons, we have covered all of Newton's laws. So, in order to get a better understanding of why they are important to us, let us look at a few examples and applications.

First, lets find out how to calculate our mass given our weight. This task is relatively simple when dealing with pounds in the English system because pounds of force is equal to pounds of mass on Earth. However, in the metric system, there is a more striking difference between weight and mass. Think of weight as the force you apply on the ground when you stand on it. Mass on the other hand is a quantity which is consistent with or without the presence of gravity.

So, let's say someone weights 200 Newton's. In order to find mass, we have to use Newton's second law which states, Force = Mass * Acceleration. On Earth, the gravitational acceleration is 9.8 (m/s squared) So, we plug in 200 (Newton's) = Mass * 9.8 (m/s squared) and solve for mass. If you aren't sure how to solve for mass, all we do is divide both sides of the equation by 9.8. So, this particular person's mass is 20.4 kg.

In another example we can find out how much force we have to apply to accelerate an object to some given acceleration. So, for example, we want to accelerate a hockey puck at 10 m/s squared. We will say a hockey puck has a mass of .1 kg. So, we use Newton's second law and plug the values in. Force = (.1 kg) * (10 m/s squared) The force we would have to apply would be 1 Newton.

Now, it is important to remember to keep our units consistent. When inputting values into our equations, we must use meters per second squared, kilograms, and Newtons to maintain simplicity. If you have units that are different, use conversions to convert them. Conversions can be readily found using major search engines.

So, try a few of these on your own. If you aren't sure what the specific measurements are of the particular situation you are analyzing, just ballpark the measurements for practice.