Push on a stack of objects with an applied force, add friction, and watch the net force decide what happens to the speed. Load the platform, predict what will move, then check the gauge.
The lab
Sum of Forces = 0 N
Speed
0.0 m/s
00:00.00
Friction
NoneLots
0 N
0 N
0 N
Reached the edge of the screen
The size of the force and speed will remain the same until a new force is applied. Click the reset button to continue.
Applied Force
0 newtons
-5000500
Add objects to the platform
How to use this simulation
Drag a crate or fridge from the left tray onto the platform, then drag black mass blocks from the right tray to stack them on top and add mass — the crate (50 kg) is already loaded to start.
Set the Applied Force with the slider or the ◀◀ ◀ ▶ ▶▶ buttons. Positive pushes right, negative pushes left.
Drag the Friction slider between None and Lots, then press the blue ▶ button to run the simulation.
Watch the three force vectors above the stack: a blue arrow for the applied force, a red arrow for friction, and a black arrow for the net (sum) force — each points right or left and grows longer as that force gets stronger. Watch the Speed gauge too, to see how the net force changes the motion.
Notice the pusher figure lean into a push or lean back to pull, matching the direction of the applied force.
Use the checkboxes to show or hide the force vectors, values, mass labels, speed gauge, or stopwatch — and start the stopwatch separately with its own ▶ button.
Try the mystery gift box: with friction set to None, apply a known force, measure the acceleration from the speed gauge, and work out its hidden mass from F = ma.
Press the small step button to advance one instant at a time, or the orange ⟲ button to clear the platform and put everything back to the start.