Mechanics
Ball on an incline
Watch the ball speed up as it rolls down the slope.
Roll a ball down an inclined plane and measure acceleration, normal force, and friction. Ideal for teaching component forces, Newton's second law on a slope, and energy on ramps.
Gravity along a ramp
On a frictionless incline, gravity pulls the ball along the slope. Only the component parallel to the ramp accelerates the ball.
Gravity acts straight down. On a tilted surface, you resolve it into components: one parallel to the ramp (causing acceleration) and one perpendicular (balanced by the normal force). That is why a ball rolls down a hill even though gravity always points downward.
- F∥ = mg sin θ
- a = g sin θ (frictionless)
Investigation brief
Plan the question before you open the lab
The brief mirrors the prerendered page: driving question, competing predictions, variable roles, governing laws, setup, analysis and extension prompts remain visible and in this order.
Driving question
A heavier ball and a lighter ball are each released from rest at the same height on a frictionless ramp. Which one reaches the bottom faster?
Predictions to weigh
- The heavier ball reaches the bottom faster.
- Both balls reach the bottom at the same speed.
- The lighter ball reaches the bottom faster.
Variable roles
What you set:
- Mass (kg)
- Ramp Angle (°)
- Height Dropped (m)
What you measure:
- Gravitational PE (J)
- Speed at Bottom (m/s)
How the investigation runs
- Open the Incline preset. Note the ramp's tilt angle and the ball's mass and its starting height above the base of the ramp.
- Use the Properties panel to set the ball's mass and the ramp's angle for this trial, and note the ball's vertical starting height above the base of the ramp.
- Run the simulation and record the ball's speed reading (probe) just as it reaches the bottom of the ramp.
Governing equation
Gravitational Potential Energy — PE = m·g·h
The ball's height above the base of the ramp stores gravitational PE before release — the energy budget that converts into motion as it rolls down.
Kinetic Energy — KE = ½·m·v²
On a frictionless ramp, all of the starting PE has converted to KE by the time the ball reaches the bottom, which is what fixes its final speed.
What the printable worksheet asks students to work out
- For each row, compute 1/2 m v^2 using your measured bottom speed. Compare it to the Gravitational PE column. What do you notice?
- Your three trials use different ramp angles. Does changing the angle alone, with the same starting height, change the final speed? Use energy conservation to explain why or why not.
Where this shows up beyond the lab
- Your Gravitational PE column depends on mass, but the measured final speed does not. Explain why a heavier ball doesn't reach the bottom faster than a lighter one on a frictionless ramp.
- A real ramp has some friction, and a real rolling ball also has to spend some of its energy spinning up as it rolls. Would you expect a real ball's final speed to be higher or lower than your frictionless prediction? Why?
- AP Physics 1 — Unit 3: Work, Energy, and Power
- AP Physics C: Mechanics — Unit 3: Work, Energy, and Power
- IB Physics — A.3 Work, energy and power
- General High School Physics — Work, energy & power
- NGSS High School Physics — Energy accounting in systems
- Middle School Physical Science — Force, mass, and motion
- Predict: does mass matter?
- Change: double the ball's mass
- Run: capture two trials
- Read the graph
- Explain: the surprising result
Open the interactive simulation to build the scene, press Play, and explore with live measurements and a guided tutorial.