Student Handout
General Activity Contract
| Part Description | Notes | Download |
|---|---|---|
Rigid Body  |
The brass grommets provide attachment points for the spring scales. Screws could have been used, but grommets allow students to put a pen or pencil through the Rigid Body and make a mark at the exact center of the spring scale attachment point. Quantity: 1 |
PDF File |
Spring Scales  |
We modified Rapala-brand (15-lb (7 kg)) spring scales by replacing the hook with a stainless steel rod. A washer having a13mm inside diameter and 27mm outside diameter was welded to one end of the rod,and the other end was threaded to accept the as-supplied retaining nut. As supplied, the scale read in "kg" and “lb”. We made a replacement label (see below) so it would read in Newtons (N), a proper unit of force. Quantity: 4 |
PDF File |
Spring Scale Label  |
This label can be printed on self-adhesive paper and attached to the body of the spring scale so that it reads in Newtons (a proper unit for force). Quantity: 1 |
PDF File |
Clips A  |
Each clip holds one wire parallel to the spring scale extension rod to which it is attached. The circular side arms on the clip are made to wrap along a washer with at 27mm outside diameter, and the lower groove of the clip is designed to grasp the 2.8mm-diameter spring-scale rod. The clips have three different heights so thatthe wires will clear each other when they are used to study the Principle of Concurrent Forces. The upper groove of this design (Clips A) is sized to grasp wires that are1.85mm in diameter. Quantity: 1 of each design |
For use with 1.85mm-diameter wire. Print clips from a semi-rigid plastic. |
Clips B  |
Revisions were carried out to improve the durability of the clips. The new clips were made of a rubber-like polymer and were designed to attach to 2.8mm-diameter wires along both their top and bottom edges. Quantity: 1 of each design |
2.8mm-diameter wire. Print clips from a flexible polymer. |
Wires  |
We used stainless steel wires. Aluminum wires were found to acquire plastic set if not handled carefully, and the resulting out-of-straightness affected their function. Our wires were 220mm-long, and 1.85 or 2.8mm-diameter, depending on which clips were used. Quantity: 3 |
|
Protractor  |
The protractor is used to measure the angles between the spring scales. Quantity: 1 |