How things move, why they move, and what stays the same. Each lesson starts from one question: you guess, run the simulation, then see why.
Kinematics is ready. Dynamics and Energies are coming soon.
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How things move: position, velocity and acceleration, without asking why.
If you drive twice as fast, how much further do you need to stop?
A sprinter's run is recorded as distance against time. When does she reach top speed, and what is it?
You drop a stone into a well and hear the splash 2.0 s later. How deep is the well?
Throw a ball straight up at 15 m/s. How high does it go, and how fast is it when it lands back in your hand?
A ball rolls off a table at the same moment another is dropped from the same height. Which lands first?
What launch angle throws the furthest?
From a clifftop, is 45° still the best angle?
A ball kicked at 16 m/s must land 20 m away. Which angles work?
You swim straight across a river while the current pulls you sideways. Where do you land, and where should you aim?
Why motion changes: forces, momentum, turning and gravity.
When a bus brakes hard, you lurch forward. What pushed you?
The same engine force drives an empty van and a loaded van. How much sooner does the empty one reach 20 m/s?
Why does a bathroom scale in a lift read more as the lift starts going up?
A horse pulls a cart, and the cart pulls back on the horse just as hard. So how does anything move?
A box sits still on a gentle ramp. How steep can the ramp get before it slides?
Why does a skydiver stop speeding up?
Why does a real football land short of the 45° prediction?
A luggage scale is just a spring. How does it turn the weight of your bag into a number?
Why does an airbag save a driver who stops from the same speed either way?
Two skaters stand still and push off each other. Who moves faster, and how much faster?
Two pucks collide at an angle. Where do they go?
Where must a 30 kg child sit to balance a 75 kg parent on a seesaw?
A painter walks along a plank resting on two supports. How far can she go before it tips?
Why doesn't a ladder against a wall slip — and when does it?
Push a tall box along the floor. Does it slide first or topple first?
Why doesn't the water fall out of a bucket swung over your head?
Why are fast motorway bends and velodromes tilted?
A door opens easily at the handle but hardly moves when pushed near the hinge. What decides how quickly it swings?
Why does a figure skater spin faster when she pulls her arms in?
Why doesn't the Moon fall down onto the Earth?
How long is a year on Mars?
What a motion can do: work, energy, power — and the oscillations that trade energy back and forth.
Is it easier to push a crate up a ramp than to lift it straight onto the truck?
At what angle should you pull a sledge?
A skateboarder drops into a 3.0 m half-pipe. How fast is she at the bottom — and does the shape of the ramp matter?
A straight ramp and a curved ramp start and end at the same points. Which ball arrives first?
How fast must you throw something so that it never comes back?
A solid ball and a hollow ball race down the same ramp. Which wins?
A car brakes to a stop. Where did all its kinetic energy go?
You run up the stairs and your friend walks up. You both did the same work — so what's different?
Two identical cars collide and stick together. Momentum is conserved — so where does the kinetic energy go?
A toy launcher's spring, squashed 5 cm, fires a ball 3 m up. How high does it go if you squash it 10 cm?
A car bounces on its springs after a small bump and after a big one. Which bounce takes longer?
How long must a pendulum be to tick once every second — and does the bob's mass matter?
Why can people walking in step make a footbridge sway?