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Centripetal Force

Apparatus

(Order Code CFA)

The Centripetal Force Apparatus (CFA) facilitates

the study of circular motion. It allows students to

easily and accurately see the relationship between

centripetal force, tangential velocity (or angular

velocity), radius and mass. The traditional method, i.e., twirling a rubber stopper in a

horizontal circle, is instructional in that students can have kinesthetic understanding

of the relationships. For example, they can feel the change in the force as the radius

changes. The CFA allows students to make direct measurements of the variables and

to obtain excellent quantitative data.

With this equipment, students are able to investigate relationships between

 Centripetal force and the mass of the accelerating object

 Centripetal force and the radius of the motion

 Centripetal force and the tangential velocity of the accelerating object

 Centripetal force and the angular velocity of the accelerating object

 Angular acceleration, torque and moment of inertia

What is included with the Centripetal Force Apparatus?

 Rectangular Frame

 Support Legs (2)

 Rotating Assembly consisting of Rotational Shaft, Encoder Wheel, 3-Step Pulley,

Rotating Beam, Bearing Housing

 Sliding Carriage to hold the test masses

 Counterbalance Carriage to balance the rotating beam

 Swivel Assembly (connects Sliding Carriage to a Dual-Range Force Sensor)

 Ultra Pulley

 Ultra Pulley Bracket (preinstalled on Assembly)

 Photogate Bracket with 1/4 x 20 mounting screw (preinstalled on Assembly)

 Dual-Range Force Sensor Bracket (preinstalled on Assembly)

 50 g masses (4)

 100 g masses (4)

 Hook (attaches a Wireless Dynamic Sensor System (WDSS) to the Sliding

Carriage)

 WDSS Mounting Screw and T Nut to secure a WDSS

A Closer Look at the Components

Rectangular Frame

The frame supports the Rotating Assembly and it accommodates a variety of

sensors. Two Pulley Guides on the top of the frame allow a Dual-Range Force

Sensor to be connected to a carriage that slides along the Rotating Beam.

Summary of content (10 pages)

PAGE 1
Centripetal Force Apparatus (Order Code CFA) The Centripetal Force Apparatus (CFA) facilitates the study of circular motion. It allows students to easily and accurately see the relationship between centripetal force, tangential velocity (or angular velocity), radius and mass. The traditional method, i.e., twirling a rubber stopper in a horizontal circle, is instructional in that students can have kinesthetic understanding of the relationships.
PAGE 2
Rotating Assembly The Rotating Assembly consists of a Rotating Beam, Rotational Shaft, Bearing Housing, Encoder Wheel, and 3-Step Pulley. Carriages are placed on the Rotating Beam. A string can be attached to the 3-Step Pulley to apply a torque to the Rotational Shaft. Swivel Assembly The Swivel Assembly consists of two strings and a swivel. The assembly is used to connect the Sliding Carriage to a Dual-Range Force Sensor. A small screw on one end of the assembly connects to the end of the force sensor.
PAGE 3
Ultra Pulley and Pulley Bracket The Ultra Pulley and Pulley Bracket allow a torque to be applied to the Rotational Shaft. Secure the Ultra Pulley to the bracket using the included 1/4 x 20 screw. Attach one end of a string to the 3-Step Pulley mounted on the Rotational Shaft. Attach a small mass to the other end of the string. Run the string over the Ultra Pulley and allow it to fall to apply a torque to the Rotational Shaft. Rectangular Frame stored flat.
PAGE 4
Attaching the Sliding Carriage to the Rotating Beam Using Sensors with the Apparatus While investigating centripetal force with this apparatus, students use sensors to measure force and angular velocity. Our recommendation is to use the Dual-Range Force Sensor to measure force and the Vernier Photogate to measure angular speed. The Vernier Wireless Dynamic Sensor System can also be used to measure force. The following describes how to connect each sensor to the apparatus. Counterbalance Carriage on left.
PAGE 5
Removable Pulley Guide on Rotating Beam Dual-Range Force Sensor attached to frame, and with screw end of Swivel Assembly attached. Vertical adjustment screw on the right. Attaching a Photogate A photogate can be attached to the Vernier Photogate Bracket, which is positioned next to the Encoder mounted on the Rotating Shaft. Follow these assembly instructions: 1. Locate the Photogate Bracket on the lower horizontal piece of the frame. 2. Secure the photogate into the stand with the 1/4 x 20 mounting screw.
PAGE 6
Data-Collection Overview and Software Setup Sensors used with the CFA provide a reading of the force required to keep the Sliding Carriage in position (the centripetal force) and the angular speed of the rotating beam. Data can be collected from both sensors simultaneously, but the software data-collection mode choices will depend on your goals and the particular sensors chosen. In order to discuss common data-collection modes used with this apparatus, let us first examine a few experiments for context.
PAGE 7
Your graphs show how centripetal force varies with angular velocity. Now take additional data with other masses and other radii. Tangential Velocity – LabQuest App with Dual-Range Force Sensor and Vernier Photogate Angular Velocity – LabQuest App with Dual-Range Force Sensor and Vernier Photogate Data collection with the Dual-Range Force Sensor and Vernier Photogate is simplified because the LabQuest App automatically calculates the interpolated force.
PAGE 8
LabQuest with Wireless Dynamic Sensor System (WDSS) Start LabQuest App, let it auto-ID the photogate. Establish a Bluetooth connection to the WDSS. When using a photogate, you will need to set the position increment in photogate motion timing to either 1/10 of the circumference (for tangential velocity) or 2π/10 (for angular velocity). 1. On the Meter tab of the LabQuest App, tap Mode. 2. Tap User Defined. 3. Enter the desired position increment as the User Defined value. 4.
PAGE 9
Other Products for Use with this Kit Dual-Range Force Sensor (DFS-BTA) This low-cost force sensor has two ranges: –10 to +10 N and –50 to +50 N. It can be easily mounted on a ring stand or dynamics cart, or used as a replacement for a spring scale. Use it to study friction, simple harmonic motion, impact in collisions, or centripetal force. Warranty Vernier warrants this product to be free from defects in materials and workmanship for a period of five years from the date of shipment to the customer.
PAGE 10
Vernier Software & Technology 13979 S.W. Millikan Way  Beaverton, OR 97005-2886 Toll Free (888) 837-6437  (503) 277-2299  FAX (503) 277-2440 info@vernier.com  www.vernier.com Revised 1/7/2015 Logger Pro, LabPro, LabQuest, and Vernier and caliper design are our registered trademarks. All other marks not owned by us that appear herein are the property of their respective owners, who may or may not be affiliated with, connected to, or sponsored by us. Printed on recycled paper.