Newton’s Laws of motion are fundamental laws that help govern both motion and kinematics.
First Law: Law of Inertia
“A body remains at rest, or in motion at a constant speed in a straight line, unless acted upon by an unbalanced force.”
In other words, an object that is in equilibrium (all forces cancel out) will maintain it’s velocity. Take a box on a table. Due to the gravitational and normal forces cancelling each other out, the box is in equilibrium. If you push down on the box, it will attempt to move downwards.
This law is mostly useful when determining whether an object is in equilibrium or not.
Second Law: Law of Acceleration
”A body’s acceleration is proportional to the force being applied on it divided by it’s mass”
In other words:
- = Force (in Newtons, N)
- = Mass (in kilograms, kg)
- = Acceleration (in )
Third Law: Law of Action and Reaction
”If two bodies exert forces on each other, these forces have the same magnitude but opposite directions”
In other words, forces always exists in pairs. When object A applies a force to object B, a reactive force is applied to A from B. The normal force is proof of this, as it is the reaction force to gravitational force.
