Activity P10: Atwood's Machine

(Photogate/Pulley System)

Concept

DataStudio

ScienceWorkshop (Mac)

ScienceWorkshop (Win)

Newton's Laws

P10 Atwood’s.DS

P13 Atwood's Machine

P13_ATWD.SWS

Equipment Needed

Qty

Equipment Needed

Qty

Photogate/Pulley System (ME-6838)

1

String (SE-8050)

1

Mass and Hanger Set (ME-8967)

1

Universal Table Clamp (ME-9376B)

1

What Do You Think?

The purpose of this activity is to study the relationship among force, mass, and acceleration using an Atwood’s Machine apparatus. What is a real world application of Atwood's Machine?

Take time to answer this question in the Lab Report section.

Background

The acceleration of an object depends on the net applied force and the object’s mass. In an Atwood's Machine, the difference in weight between two hanging masses determines the net force acting on the system of both masses. This net force accelerates both of the hanging masses; the heavier mass is accelerated downward, and the lighter mass is accelerated upward.

Based on the above free body diagram, T is the tension in the string, M2 > M1, and g is the acceleration due to gravity. Taking the convention that up is positive and down is negative, the net force equations for M1 and M2 are:

Assuming that the pulley is massless and frictionless, and the string has no mass and doesn’t stretch, let T 1 = T 2. Solving for a, the acceleration of the system of both masses, the theoretical acceleration is g times the difference in mass divided by the total mass:

SAFETY REMINDERS

Follow all directions for using the equipment.

For You To Do

Use the Photogate/Pulley System to measure the motion of both masses as one moves up and the other moves down. Use DataStudio or ScienceWorkshop to record the changing speed of the masses as they move. The slope of the graph of velocity vs. time is the acceleration of the system.

PART I: Computer Setup

1. Connect the ScienceWorkshop interface to the computer, turn on the...