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Physics

Atwood Machine Calculator

Find ideal acceleration and rope tension for two masses on a frictionless pulley.

SI units shown beside each fieldIdeal model explained below
Physics lab
Physics lab

Use the units beside each input and review the model assumptions.

See the method

Define your system

Runs on your device

Your calculated quantity

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter mass 1, mass 2, gravity.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Acceleration toward mass 2 = g(m2−m1)/(m1+m2); tension = 2m1m2g/(m1+m2).

A WORKED EXAMPLE

Using mass 1 = 3 kg, mass 2 = 5 kg, gravity = 9.80665 m/s², the result is 2.4516625 m/s². Change these example inputs to match your task; use the method above to check each step.

Understanding your result

Massless rope and pulley, no friction. A positive acceleration means mass 2 descends.

What to keep in mind

Massless rope and pulley, no friction. A positive acceleration means mass 2 descends. An idealized educational model using the stated SI units. Real systems may need additional forces, losses or experimental measurements. Not a safety or equipment specification.

Common questions

How do I use this atwood machine calculator?

Find ideal acceleration and rope tension for two masses on a frictionless pulley. Enter mass 1 in kg, mass 2 in kg, gravity in m/s². The starting example is editable; use values for the same system or project.

Which assumptions affect this result?

Massless rope and pulley, no friction. A positive acceleration means mass 2 descends.

Methodology maintained by ClarityKit. How these tools are built and checked.