Mechanics & Motion
Discover why a ball falls, how a rocket launches, and what keeps the Moon in orbit. This is where physics begins — with the simple question: why do things move?
"Imagine you're on a skateboard. You're not moving — until someone gives you a push. That push is a force, and it changes your motion. That's really all there is to it!"
Motion is simply a change in position over time. When you walk to school, ride a bike, or throw a ball, you're creating motion. Physicists describe motion using three key ideas: how far something goes (distance), how fast it goes (speed), and whether it's speeding up or slowing down (acceleration).
Isaac Newton figured out three simple rules that explain almost all motion we see around us. These are called Newton's Laws of Motion, and they're the foundation of mechanics — the branch of physics that studies how and why things move.
A cheetah can accelerate from 0 to 60 mph in just 3 seconds — that's faster than most sports cars!
"Newton's laws are beautifully simple. The first says: things keep doing what they're doing unless something messes with them. The second says: push harder, go faster. The third says: every push gets a push back. That's it — three rules that explain almost everything!"
First Law (Inertia): An object at rest stays at rest, and an object in motion stays in motion at the same speed and direction — unless a force acts on it. This is why you lurch forward when a car suddenly stops: your body wants to keep moving!
Second Law (F = ma): The acceleration of an object depends on the force applied and the object's mass. Push a shopping cart and it moves easily. Push a truck with the same force? Barely budges. More mass means more force needed.
Third Law (Action-Reaction): For every action, there is an equal and opposite reaction. When you jump, your feet push down on the ground, and the ground pushes you up. Rockets work the same way — they push hot gas downward, and the gas pushes the rocket upward!
Newton supposedly discovered gravity when an apple fell on his head. While the apple part might be true, it definitely didn't bonk him — he just watched it fall and wondered why.
"Every piece of matter in the universe attracts every other piece. You're attracted to the Earth, but the Earth is also attracted to you! The reason you fall down and not up is simply that the Earth is much, much heavier than you."
Gravity is the force that pulls objects with mass toward each other. It's what keeps your feet on the ground, the Moon orbiting Earth, and the Earth orbiting the Sun.
The strength of gravity depends on two things: how much mass the objects have, and how far apart they are. The bigger the masses, the stronger the pull. The farther apart, the weaker the pull.
On Earth, gravity accelerates everything at about 9.8 meters per second squared (9.8 m/s²). This means a falling object gets 9.8 m/s faster every second it falls — whether it's a feather or a bowling ball (in a vacuum, they fall at exactly the same rate!).
If you could stand on Jupiter, you'd weigh about 2.5 times more than on Earth because Jupiter's gravity is much stronger!
Experiment & Discover
Play with the simulation below to see physics in action!
Projectile Motion
Adjust the angle and speed, then launch to see the parabolic trajectory!
Test Your Understanding
As Feynman said: "If you can't explain it simply, you don't understand it well enough."
A hockey puck slides across ice with very little friction. According to Newton's First Law, what will the puck do?
Where You'll See This
Physics isn't just in textbooks — it's everywhere around you!
Seatbelts protect you because of inertia — your body wants to keep moving forward even when the car stops suddenly
Rockets work by pushing exhaust gas backward (Newton's Third Law pushes the rocket forward)
A figure skater spins faster by pulling their arms in — this is conservation of angular momentum
Satellites orbit Earth because gravity constantly pulls them toward Earth while their forward motion keeps them from falling straight down