Atwood's Machine - SA-9241



Two Super Pulleys mounted on a 6.4 cm long rod produce a classic, low-friction introduction to Newton's Second Law.

The Atwood’s Machine is ideal for demonstrating and analyzing the gravitational acceleration and force. In an ideal Atwood’s Machine, two unequal masses are attached to a flexible, massless string which passes over a frictionless, massless pulley. The unequal gravitational forces acting on the two masses provide a constant force that accelerates both masses. The heavier mass is accelerated downward and the lighter mass is accelerated upward.

A real Atwood’s Machine is not as simple as its ideal counterpart. The string is not massless and the pulley is not frictionless. The rotational inertia of the pulley also reduces the simplicity of the ideal Atwood’s Machine. By using two low friction pulleys at each end of a connecting rod, the effects of friction and rotational inertia are effectively reduced to a minimum.


Buying Guide

Photogate Head
Smart Gate
Recommended - One of the following

The Atwood's Machine may be used for demonstration purposes but to make the activity quantitative add a photogate or Smart Gate along with an interface and PASCO software to perform data collection and analysis.

Photogate Head   ME-9498A
Smart Gate   PS-2180
Base and Support Rod
Adjustable Angle Clamp
Mass and Hanger Set
Base and Support Rod   ME-9355
Adjustable Angle Clamp   ME-8744
Mass and Hanger Set   ME-8979

Interface Required

To use this product you need a PASCO interface. 

New to probeware or have questions about  sensors or interfaces? Contact Teacher and Technical Support.  We're here to help!

Software Required

SPARKvue software or PASCO Capstone software may be used. PASCO Capstone is available for Mac and Windows. SPARKvue is available for Mac, Windows, iOS, Android and Chromebooks.

Learn more about Bluetooth Compatibility.