Sir Isaac Newton proposed the laws of motion in 1687. Newton’s law describes the motion of macroscopic objects; by using these laws, we can calculate the initial and final velocity of the object, as well as acceleration and other related variables that explain the motion of an object. Let’s discuss these laws one by one with examples.
Newton’s first law of motion
First law of motion is known as the “law of inertia.” “Inertial” refers to an object’s tendency to resist changes in its state, whether it is in rest or motion.
Statement:
“A body at rest will remain at rest, and a body at motion will remain at motion until we do not apply an external force.” According to this law, external force can be gravity, drag, or any other applied force.
Example:
For stationary objects (the object at rest is called stationary), a book lying on the table remains at the table until an external force is not applied to move it or displace it.
For moving bodies, if a football is moving horizontally, keep starting its motion until a force does not influence the motion of this ball.
- Newton’s second law of motion describes the relationship between force, mass, and acceleration. We can calculate how much force is required to accelerate the unit mass for a specific distance.
Newton’s second law definition
According to 2nd law, a body’s acceleration is directly proportional to the applied force, and acceleration is inversely proportional to its mass.”.
Explanation
This law explains the fundamental relation between force and acceleration, the greater the applied force, the greater will be acceleration, and vice versa. The second part clarifies that a greater object’s mass results in a smaller acceleration. The object moves in the direction of the applied force.
Mathematically
a ∝ F……..(1)
a ∝ 1/m…..(2)
Combine both equations and rearrange. Then
F=ma
Here
- F is the applied force on an object( measured in Newton)
- “a” is acceleration occurred due to force(measured in m/sec)
- M is the mass of a given object
In short, this law explains the change in velocity of an object under the influence of any force and gives a quantitative explanation of these three parameters that are mentioned above.
Newton’s third law of motion
What is Newton’s third law?
Newton’s 3rd law explains the relation between force and its reaction, there a two classifications of forces contact and non-contact both have the opposite reaction.
Definition
“Every action has a reaction but the reaction occurred in opposite direction”
Explanation
Whenever two bodies interact with each other they exert force on each other these forces are known as action and reaction forces. This means if an object(A) exerts a force on object (B) then the object (B) will be applied reaction force on object (A) but in the opposite direction.
FAB= –FBA
Rocket launching
Examples
In rocket launching Newton’s third law of motion is used in the form of action and reaction by gasses. To launch a rocket we use gasses in the tail of the rocket, when we ignite the gasses they move back and push the rocket in an upward direction.
Swimming
In swimming, water when a swimmer pushes the water as an action then water exerts reaction force and floats the swimmer in the opposite direction.
Aircraft engine
The engine of the jet exhausts gasses back as an action and gasses exert force on the jet which flies as a result of reaction force.
Limitations of Newton’s laws under SphereMedium
As per as spheremedium plarform says Newton’s laws of motion are foundational but have limitations. They are accurate only for objects at non-relativistic speeds and do not apply to quantum-scale particles, where quantum mechanics is needed. In strong gravitational fields and large-scale cosmological systems, general relativity provides better descriptions. Additionally, Newton’s laws assume inertial frames andstruggle with non-linear or complex systems, making them less effective in such contexts
Useful Links
- Britannica | Newton’s laws of motion | Definition, Examples, & History
- NASA Glenn Research Center | Newton’s Laws of Motion
- BYJU’S | Newton’s Laws of Motion
- Wikipedia | Newton’s laws of motion
- BYJU’S | Newton’s First Law Of Motion – Definition, External Force, …
- Savemyexams | Newton’s Laws of Motion (CIE A Level Physics)
