(This article was translated from Japanese to English using DeepL.)
Now that we have finished accelerating motion, let’s start learning about force.
Various kinds of forces, such as gravity, friction, and normal force, have been introduced in science courses up to junior high school.
There are many different types of forces, but what exactly is a “force”?
Definition of force in physics
We will go on to calculate the magnitude of the force or use the force acting on an object to investigate the motion of that object.
To do so, let us first define exactly what force is.
In physics, a force is defined as anything that causes an object to deform or change its state of motion.
However, high school physics almost never deals with deformation of objects.
Thus, what is important is the force as the cause of the change in the state of motion.
To change the state of motion means to change the speed or direction of motion of an object.
How to represent force
Finally, let’s review how force is represented.
Since force is a quantity with direction, it is represented by an arrow.
What is important in force is “magnitude, direction, and point of action”.
These are called the three elements of force and correspond to the “length, direction, and starting point of the arrow”.
The straight line along the arrow of a force is called the line of action of that force.
Check it out in the summary note below!
Summary of this lecture
Starting in the next lecture, we’ll study forces that appear frequently in physics!