Newton's Second Law tells us how things move when they are pushed or pulled.

It says that the acceleration (how fast something speeds up) of an object depends on two things: the net force (the total force acting on it) and its mass (how heavy it is).

We can write this as:

$$F_{net} = m \cdot a$$

Types of Forces

There are two main types of forces:

1. Contact Forces: These forces happen when objects touch each other.

   • Friction: This is the force that works against motion. It changes depending on the surfaces that are touching.
   • Tension: This is the force that's passed through a rope or string when it's pulled.

2. Non-Contact Forces: These forces can work even when things are not touching.

   • Gravitational Force: This is the force that pulls objects towards each other, like how the Earth pulls us down. It can be calculated with the formula: $F = \frac{G \cdot m_1 \cdot m_2}{r^2}$ (Here, $G$ is a constant number that helps us measure this force.)
   • Electromagnetic Forces: These forces act between particles that carry an electric charge.

Knowing about these different forces is important. It helps us understand and use Newton's Second Law in real-life situations.