​​​​​​​ Laws of Motion and Gravity

👨‍🔬 Isaac Newton’s Contributions

In the late 1600s, Sir Isaac Newton formulated the Three Laws of Motion and the Law of Universal Gravitation, which laid the foundation for classical mechanics.

🌀 Newton’s Three Laws of Motion

✅ 1st Law: Law of Inertia

“An object at rest stays at rest, and an object in motion stays in motion at a constant velocity, unless acted upon by a net external force.”

🔍 Meaning:

• If nothing pushes or pulls on an object, it won’t change its state.

• This law explains why seat belts are needed — your body wants to keep moving when the car suddenly stops.

🧠 Example:

• A soccer ball on the ground won’t move until someone kicks it.

• A moving skateboard keeps rolling until friction or a foot stops it.

✅ 2nd Law: Force = Mass × Acceleration (F = m × a)

“The acceleration of an object depends on its mass and the force applied to it.”

🔍 Meaning:

• Heavier objects need more force to accelerate.

• The greater the force, the greater the acceleration.

🧠 Example:

• It’s easier to push an empty cart than a full one.

• A baseball thrown with more force moves faster.

✅ 3rd Law: Action = Reaction

“For every action, there is an equal and opposite reaction.”

🔍 Meaning:

• When one object pushes another, the second object pushes back equally, in the opposite direction.

🧠 Example:

• When you jump, your feet push the ground down — and the ground pushes you up.

• Rockets launch upward by pushing gas downward.

🌍 Newton’s Law of Universal Gravitation

“Every object in the universe attracts every other object with a force proportional to their masses and inversely proportional to the square of the distance between them.”

📘 Formula:

F=Gm1m2r2F = G \frac{m_1 m_2}{r^2}

Where:

• F = gravitational force

• G = gravitational constant

• m₁ and m₂ = masses of two objects

• r = distance between their centers

🔍 Meaning:

• Larger masses pull with stronger force (e.g., Earth pulls you strongly).

• As distance increases, gravity decreases rapidly.

🧠 Example:

• The Moon orbits the Earth due to gravity.

• Tides on Earth are affected by the Moon’s gravitational pull.

⚖️ Summary Table