PASCO SA-9241 Pulley Atwood’s Machine - Manual

I n s t r u c t i o n S h e e t
012-04152B
Pulley Atwood’s Machine
SA-9241
800-772-8700 www.pasco.com
®
*012-04152*
Introduction
The PASCO Pulley Atwood’s Machine is based on a device cre-
ated by the Reverend George Atwood in 1784 to help demon-
strate the mysteries of acceleration and force. In an ideal
Atwood’s Machine, two unequal masses are attached to a flexi-
ble, massless string which passes over a frictionless, massless
pulley. (Please see Figure 1 below). The unequal gravitational
forces acting on the two masses provide a constant force that
accelerates both masses. The heavier mass is accelerated down-
ward 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.
PASCO scientific provides the Atwood’s Machine shown above.
Two ME-9450A Super Pulleys are mounted on a 6.3 centimeter
(2.5 in) long, 0.9 cm (0.375 in) diameter rod. The connecting rod
is easily mounted on standard lab rod clamps* (not included).
The PASCO Pulley Atwood’s Machine (SA-9241) can handle
masses up to a few kilograms.
Operation
The Atwood’s Machine can be used with a Photogate Head,
PASCO computer interface, and PASCO data aquisition software
to allow measurement of the motion of one of the pulleys.
• Remove the Super Pulley from one end of the Connector
Rod.
• Put the threaded end of the Connector Rod through the slot
on the edge of the Photogate Head (see Figure 3).
• Re-connect the Super Pulley to the Connector Rod.
• Connect the Photogate Cable to the Photogate Head and plug
the cable into a digital channel of a PASCO computer inter-
face. (Note: For a PASCO interface without digital channels,
use a PS-2159 Digital Adapter.)
ME-9450A Super Pulley
Connector Rod
Thumbscrew
Figure 1
Figure 2