PASCO ME-6855 Tension Protractor - Manual (Page 9)

®
T e n s i o n P r o t r a c t o r E x p e r i m e n t 2 : B o o m i n S t a t i c E q u i l i b r i u m
7
Experiment 2: Boom in Static Equilibrium
Purpose
The purpose of this experiment is to examine the two requirements for a boom to be in
equilibrium and use them to determine the forces acting on the boom at the pivot.
Pre-lab Questions
1. What are the two requirements for an extended object to be in equilibrium?
2. Does the tension of the string shown in Figure 2.1 cause a clockwise or counterclock-
wise torque about the pivot?
3. Does the hanging mass shown in Figure 2.1 cause a clockwise or counterclockwise
torque about the pivot point?
4. Where does the weight of the boom (in this case, the meter stick) act?
5. Which angle will you measure with the Tension Protractor (in Figure 2.1)?
Theory
There are two requirements for an object in equilibrium:
1. The vector sum of the forces acting on the object in equilibrium is zero:
(eq. 2-1)
2. The vector sum of the torques acting on the object in equilibrium is zero:
(eq. 2-2)
Counterclockwise torques are defined to be positive and clockwise torques are negative.
Torque is calculated using
, where r is the lever arm distance measured
from the pivot to the point where the force (F) is applied, and
θ is the angle between the
lever arm (r) and the applied force (F).
Equipment Needed Suggested Part
• Tension Protractor ME-6855
• Large Table Clamp ME-9472
• Multi Clamp SE-9442
• Hooked Mass Set SE-8759
• Braided Physics String SE-8050
• Level SE-8729
• (2) 90 cm Steel Rods ME-8738
• Balance SE-8723
• Meter Stick with a hole in each end
(requires drilling 8 mm or 5/16 inch
holes) SE-8729
• short rod, about 6 mm (1/4 inch) in
diameter and 15 cm (6 inches) long
F
i i
∑
0 =
τ
i i
∑
0 =
τ
r
θ
sin
( )F
=