## Capacitance of capacitor

### Definition of the Capacitance of capacitor

A small glass can contain a little water, while a large glass can contain more water. The larger the volume of glass, the more water that can be contained. So, each glass has the capacity or size of the ability to contain water. Like glass, capacitors also can store the electrical charges and the electrical potential energy. Capacitor capacity to store the electrical charge and the electric potential energy is called capacitance.

Factors affect capacitance

The size of the glass’s ability to contain water is determined by the volume of the glass. What about capacitors, what determines the size of the capacitor’s ability to store the electric charge?

### 1. Quantities of vector and scalar

In addition to the fundamental and derived quantities, physical quantities can still be divided into two other types, namely scalar quantities and vector quantities. Quantities such as mass, distance, time and volume, are scalar quantities, quantities that only have magnitude but have no direction. Whereas magnitudes such as displacement, velocity, acceleration, and force are vector quantities, quantities that have magnitude and also have direction.

a. Difference between scalar and vector quantity

If you say the mass of a ball is 400 grams, this statement is enough for you to know the mass of the ball. You don’t need direction to find out the mass of the ball. Likewise with time, temperature, volume, density, etc. There are several physical quantities that cannot be expressed in magnitude only. If you say a child moves as far as 100 meters, then this statement is not enough. You might ask, where did he move? Is it north, south, east, or west? Likewise, if you say that you push the table with a force of 200 N.

## Quantities of physics in the linear motion

### 1. Time interval

When an object moves from one place to another, the object needs a certain time interval. The time symbol is t (time). The international system unit of time is second (s).

### 2. Distance and displacement

Distance is the length of the path taken by an object. Distance is a scalar quantity, where the quantity does not depend on direction. The distance symbol is d and the international system unit is a meter (m).

## Uniform linear motion

### Definition of the uniform linear motion

An object experiences uniform linear motion if the velocity of the object is constant. Velocity includes the magnitude and direction of velocity. Direction of velocity = direction of displacement = direction of movement. The direction of the velocity of a constant object = the direction of motion of a constant object, or the direction of motion of a fixed object = the object is moving straight. The magnitude of velocity or speed is constant = the speed is always the same all the time.

## Nonuniform linear motion

### Definition of nonuniform linear motion

Nonuniform linear motion is motion at constant acceleration. In other words, nonuniform linear motion = motion with the magnification of acceleration is constant and the direction of acceleration is constant. Direction of acceleration is constant = direction of velocity is constant = direction of displacement is constant = direction of motion is constant = the object moves in a straight line. The magnitude of constant acceleration means that the magnitude of velocity or speed increases regularly.

## Free fall motion

### Article about the Free fall motion

In everyday life, we often see objects that experience free-fall motion, for example, the motion of fruit falling from a tree, the motion of objects that fall or are dropped from a certain height. Why do objects experience free-fall motion? If observed at a glance, the object experiencing free fall as if it has a fixed speed, or in other words the object does not accelerate. The fact that happens, every object that falls freely experiences a constant acceleration. This reason causes free-fall motion, including the example of nonuniform linear motion. How to prove that objects experiencing free-fall experience constant acceleration or its speed increase?

## Uniform circular motion

### Article about the Uniform circular motion

In everyday life, we often encounter objects that move in a uniform circular motion. One example of an object that undergoes uniform circular motion is the second needle, the minute needle, and the clock needle on the analog clock. The second needle always rotates at an angle of 360o for 60 seconds (one minute) or rotates at a 6o angle for one second. The minute needle always rotates at a 360o angle for 60 minutes (one hour) or rotates at a 6o angle for one minute. Hour needle also always rotates 360o for 24 hours (one day). If an object moves in a regular circle such as a second needle, a minute needle, or a clock needle then the objects are said to be doing the circular motion. Can you think of examples of objects that move in a circular motion?

## The quantities of physics in the circular motion

The quantities of physics in the circular motion include angular displacement, angular velocity, and angular acceleration.

### 1. Angular displacement (θ)

Displacement in circular motion is called angular displacement. Angular displacement including vector quantities, therefore, has magnitude and directions. The direction of angular displacement is usually expressed in a clockwise direction (clockwise or counterclockwise).

There are three units of angular displacement. First, degree (o). One circumference of the circle is equal to 360o. Second, revolution. One circumference of the circle is equal to one revolution. Third, radian. Observe the figure below. If an object moves in a circle then r = the radius of the circle, x = the length of the circular path that the object passes = the circumference of the circle.

## Projectile motion

### Initial velocity (vo) and the component of initial velocity (vox and voy)

An object which moves parabolic always has an initial speed. Because parabolic motion is a combination of movements in the horizontal and vertical directions, the initial velocity also has horizontal and vertical components.

If the object moves parabolically as in Figure 1 and 3 then the initial velocity in the horizontal direction (vox) and the initial velocity in the vertical direction (voy) are calculated using the equation:

## Newton’s law of motion

### 1. Definition of force

Force is something that causes things to accelerate. In other words, force is something that moves, stops, or changes the direction of movement of an object. Force is a vector quantity, and therefore, has a magnitude and direction. The force symbol is F (Force). F is a general symbol of force. There are several types of forces and not all forces have the symbol F. The international system unit is kg m/s2 aka Newton.

### 2. Definition of the net force

The resultant force (ΣF) is the sum of all the forces acting on an object. Force is a vector quantity, so the total force is calculated based on the vector addition rule.