Adjustable Inclined Plane Model

Quick Answer: The Adjustable Inclined Plane Model is a hinged wooden ramp with an angle scale, a pulley at its upper end and a weight pan on a string. Students set the slope, load the pan until it balances the load on the plane, and verify the law of the inclined plane and its mechanical advantage at different angles.

Effort, Load and Angle

In the listing image the adjustable inclined plane is a smooth wooden board hinged to a wooden base and raised to an angle read on a protractor-style quadrant scale. A pulley is mounted at the top end of the board. A string from a small load carriage on the plane runs up and over the pulley to a hanging weight pan, so weights in the pan provide the effort that pulls along the slope.

On a smooth slope at angle θ, only part of the load’s weight acts down the plane, equal to W sin θ, and that is the effort needed to hold the load in balance. Effort divided by load therefore equals sin θ, which is also the height of the plane divided by its length. Low slopes need small efforts but long distances; steep slopes the reverse. In the ideal case the work done by the effort along the slope equals the work needed to lift the load vertically, which makes the apparatus a clear introduction to work and energy in simple machines, and it sits naturally with the other mechanics lab equipment used for levers and pulleys, such as the Moment of Force Apparatus.

Real planes have friction, and students can measure it. The effort that just drags the load slowly up the slope is larger than the ideal value, and the effort that just stops it sliding down is smaller; the average of the two approximates the frictionless figure. With the string removed, raising the board until a block starts to slide gives the angle of repose, whose tangent equals the coefficient of static friction. The angle range, load mass and weights supplied should be confirmed at enquiry.

Specifications

Applications

• Verifying that effort equals load multiplied by the sine of the angle
• Calculating mechanical advantage and efficiency of a ramp
• Finding the coefficient of static friction from the angle of sliding
• Discussing ramps, roads on hills, wedges and screws as inclined planes

Care & Handling

• Make sure the board is held securely at the chosen angle before adding weights to the pan.
• Keep the pulley running freely and the string free of knots and fraying.
• Keep the board surface clean and dry, as dust and moisture change friction readings.
• Place a soft pad at the foot of the plane to catch a load that runs down.

Why Choose LabEquip

Physics teachers from middle school to junior college use an inclined plane for the simple machines and friction practicals, where students take their own readings at several angles. LabEquip supplies it through the STEM kits range, and our contact page can confirm which weights come with it.

Frequently Asked Questions

What is the law of the inclined plane?

For a smooth slope, the effort needed to hold a load in balance, pulling parallel to the plane, equals the load multiplied by the sine of the angle. Equivalently, effort divided by load equals the height of the plane divided by its length.

Why does a gentler slope need less effort?

At a small angle only a small part of the load’s weight acts down the slope, so less effort balances it. The trade-off is distance: the load moves further along the plane to rise the same height, so the work done stays about the same.

How can friction be allowed for?

Measure the effort that just makes the load creep up the plane, then the effort that just stops it sliding down. Friction adds to the first and subtracts from the second, so their average approximates the frictionless value.

How is the coefficient of friction found with the plane?

Remove the string, place a block on the board and raise the angle slowly until the block just starts to slide. The tangent of that angle equals the coefficient of static friction between the block and the board.

What is the mechanical advantage of an inclined plane?

Ideally it is the load divided by the effort, which equals the length of the slope divided by its height, or one divided by the sine of the angle. Measured values are lower because of friction.

Where are inclined planes used in everyday life?

Wheelchair and loading ramps, mountain roads that zigzag up a slope, wedges such as axe heads, and screws, whose threads are inclined planes wrapped round a cylinder, all use the same principle.

Last Updated: September 2026