Lab
Force Table - Force Vectors in Equilibrium
Printer Friendly Version
Purpose: In this lab you are going to investigate static equilibrium produced by three concurrent forces.
To complete the lab you will need the
following equipment:
a force table, one washer with its three attached strings, three pulleys, and a set of hooked masses (10-500 grams).
Procedure
The first task is to attach all three strings through the washer. We will do this by folding the string in half, passing the folded end into the washer, and threading the rest of the string through the fold. Tie a knot at the end of the strings. These knots will support the hooked masses. Finally arrange the three string-loops around the washer, but do not tighten them - let them be free to move along the circumference of the washer.
At the end of each string you will attach a hooked mass: 10 grams, 50 grams, 100 grams, 200 grams or 500 grams. Each string must have a different amount of mass – no duplicates. Adjust the positions of the strings so that the central ring is in static equilibrium. The inner circumference of the ring should be equally spaced around the center “hole.” No strings may lie along angles that are multiples of 30º or 45º. Initially start you’re your largest mass attached to a string which passes over a pulley at 0º. Then add a second mass to a second pulley placed at any arbitrary position (remember to not use any of the restricted angles). Then start “playing” with the amount of mass needed and the angles needed to keep the center of the washer over the “hole.” No masses may be added to your greatest mass at 0º - otherwise you can move masses around as needed. When the system appears to be in equilibrium, please the third string over its pulley for a final test. Adjust as necessary.
Check Point (1):
Gently displace the washer and make sure it returns to equilibrium before recording your data.
Check Point (2):
Are the forces (the weights of the attached masses) all unique? (Yes/No) Remember that you are not allowed to have any duplicate values.
When equilibrium is confirmed, record the positions (in degrees) of each string and the amount of mass suspended from each string in the following table.
table angle
attached mass
equivalent force
string
(degrees)
(g)
(N)
1
2
3
Complete a scaled vector force diagram using the head-to-tail method of vector addition. Make sure to not rotate your diagram as all “relocated origins” must have their x-axes parallel to the original x-axis for your 0º force. Use a scale of 5 cm = 1 N. Placing each force vector at its appropriate angle and drawn to its proportional length. LONGER vectors produce better results.
Check Point (3):
Based on your scale of 1 N being represented by 5 cm, are each of your vectors drawn to the correct length and at the correct angle? Label your vectors with their lengths and directions (using counterclockwise angles measured from the positive-x-axis) as ordered pairs. Make sure that each force vector terminates with an arrow.
If your vectors do not “close on each other” construct and measure the “required” 4th vector to establish equilibrium. Label it on your diagram as an ordered pair. Highlight this vector in a second color.
Make sure that you diagram is correctly scaled and labelled before continuing on to the next section. Remember that each person in the group is to complete their own diagram. Consequently, the 4th vector may have slightly different values depending on the skill of the “draftsman.”
Using a calculator that has trig functions (making sure that it is set in degree mode), complete the following table. In the first column report the length (len) and direction (dir) from your vector diagram. Next calculate the x- and y-components of each vector to 2 decimal places. Include both the positives and negatives values
x = Lcos(
θ
)
y = Lsin(
θ
)
vector
(len, dir)
(cm)
(cm)
1
2
3
4
NOTE: If your diagram was constructed and measured correctly, the values for both net-x and net-y should both zero.
Refer to the following information for the next two questions.
Conclusions
Why did the value of the 3rd hanging mass change once its string was placed over its pulley in your final test?
Why do you think your group’s data was “destined” to need the 4th vector to truly set your washer into a state of equilibrium?
Refer to the following information for the next two questions.
The strong man can withstand the tension force exerted by the two horses pulling in opposite directions.
How would the tension compare if only one horse pulled and the left rope were tied to a tree?
How would the tension compare if the two horses pulled in the same direction, with the left rope tied to the tree?
Refer to the following information for the next two questions.
The right puppy is pulling on the shoe with a force of 40N at an angle 24º and the left puppy is pulling on the shoe with a force of 55N at 141º.
SHOW ALL CALCULATIONS. You may either use the calculator method or a scaled diagram. If you use a diagram, make sure to inform the reader of your scale.
If the shoe’s owner adds a third force to place the shoe into a state of static equilibrium before trying to extract the shoe from the two dogs, then what size force and should she attempt to rescue her shoe?
At what angle should she apply the force in your previous answer?
Make sure to turn in a copy of the final conclusion's calculations AS WELL AS your original force-table diagram to your instructor.
Related Documents
Lab:
Labs -
2-Meter Stick Readings
Labs -
Acceleration Down an Inclined Plane
Labs -
Addition of Forces
Labs -
Circumference and Diameter
Labs -
Coefficient of Friction
Labs -
Coefficient of Friction
Labs -
Coefficient of Kinetic Friction (pulley, incline, block)
Labs -
Conservation of Momentum in Two-Dimensions
Labs -
Cookie Sale Problem
Labs -
Density of a Paper Clip
Labs -
Determining the Distance to the Moon
Labs -
Determining the Distance to the Sun
Labs -
Eratosthenes' Measure of the Earth's Circumference
Labs -
Falling Coffee Filters
Labs -
Home to School
Labs -
Indirect Measurements: Height by Measuring The Length of a Shadow
Labs -
Indirect Measures: Inscribed Circles
Labs -
Inelastic Collision - Velocity of a Softball
Labs -
Inertial Mass
Labs -
Introductory Simple Pendulums
Labs -
Lab: Rectangle Measurements
Labs -
Lab: Triangle Measurements
Labs -
LabPro: Newton's 2nd Law
Labs -
Loop-the-Loop
Labs -
Marble Tube Launcher
Labs -
Mass of a Rolling Cart
Labs -
Moment of Inertia of a Bicycle Wheel
Labs -
Quantized Mass
Labs -
Relationship Between Tension in a String and Wave Speed
Labs -
Relationship Between Tension in a String and Wave Speed Along the String
Labs -
Static Equilibrium Lab
Labs -
Static Springs: Hooke's Law
Labs -
Static Springs: Hooke's Law
Labs -
Static Springs: LabPro Data for Hooke's Law
Labs -
Terminal Velocity
Labs -
The Size of the Moon
Labs -
The Size of the Sun
Labs -
Video LAB: A Gravitron
Labs -
Video LAB: Ball Re-Bounding From a Wall
Labs -
Video Lab: Falling Coffee Filters
Resource Lesson:
RL -
Advanced Gravitational Forces
RL -
Air Resistance
RL -
Air Resistance: Terminal Velocity
RL -
Basic Trigonometry
RL -
Basic Trigonometry Table
RL -
Curve Fitting Patterns
RL -
Dimensional Analysis
RL -
Forces Acting at an Angle
RL -
Freebody Diagrams
RL -
Gravitational Energy Wells
RL -
Inclined Planes
RL -
Inertial vs Gravitational Mass
RL -
Linear Regression and Data Analysis Methods
RL -
Metric Prefixes, Scientific Notation, and Conversions
RL -
Metric System Definitions
RL -
Metric Units of Measurement
RL -
Newton's Laws of Motion
RL -
Non-constant Resistance Forces
RL -
Potential Energy Functions
RL -
Properties of Friction
RL -
Properties of Lines
RL -
Properties of Vectors
RL -
Significant Figures and Scientific Notation
RL -
Springs and Blocks
RL -
Springs: Hooke's Law
RL -
Static Equilibrium
RL -
Systems of Bodies
RL -
Tension Cases: Four Special Situations
RL -
The Law of Universal Gravitation
RL -
Universal Gravitation and Satellites
RL -
Universal Gravitation and Weight
RL -
Vector Resultants: Average Velocity
RL -
Vectors and Scalars
RL -
What is Mass?
RL -
Work and Energy
Review:
REV -
Honors Review: Waves and Introductory Skills
REV -
Physics I Review: Waves and Introductory Skills
REV -
Test #1: APC Review Sheet
Worksheet:
APP -
Big Fist
APP -
Family Reunion
APP -
Puppy Love
APP -
The Antelope
APP -
The Box Seat
APP -
The Dognapping
APP -
The Jogger
APP -
The Pool Game
APP -
War Games
CP -
Action-Reaction #1
CP -
Action-Reaction #2
CP -
Equilibrium on an Inclined Plane
CP -
Falling and Air Resistance
CP -
Force and Acceleration
CP -
Force and Weight
CP -
Force Vectors and the Parallelogram Rule
CP -
Freebody Diagrams
CP -
Gravitational Interactions
CP -
Incline Places: Force Vector Resultants
CP -
Incline Planes - Force Vector Components
CP -
Inertia
CP -
Inverse Square Relationships
CP -
Mobiles: Rotational Equilibrium
CP -
Net Force
CP -
Newton's Law of Motion: Friction
CP -
Sailboats: A Vector Application
CP -
Satellites: Circular and Elliptical
CP -
Static Equilibrium
CP -
Tensions and Equilibrium
CP -
Vectors and Components
CP -
Vectors and Resultants
CP -
Vectors and the Parallelogram Rule
NT -
Acceleration
NT -
Air Resistance #1
NT -
An Apple on a Table
NT -
Apex #1
NT -
Apex #2
NT -
Falling Rock
NT -
Falling Spheres
NT -
Friction
NT -
Frictionless Pulley
NT -
Gravitation #1
NT -
Head-on Collisions #1
NT -
Head-on Collisions #2
NT -
Ice Boat
NT -
Rotating Disk
NT -
Sailboats #1
NT -
Sailboats #2
NT -
Scale Reading
NT -
Settling
NT -
Skidding Distances
NT -
Spiral Tube
NT -
Tensile Strength
NT -
Terminal Velocity
NT -
Tug of War #1
NT -
Tug of War #2
NT -
Two-block Systems
WS -
Advanced Properties of Freely Falling Bodies #1
WS -
Advanced Properties of Freely Falling Bodies #2
WS -
Calculating Force Components
WS -
Calculating Vector Resultants
WS -
Charged Projectiles in Uniform Electric Fields
WS -
Circumference vs Diameter Lab Review
WS -
Combining Kinematics and Dynamics
WS -
Data Analysis #1
WS -
Data Analysis #2
WS -
Data Analysis #3
WS -
Data Analysis #4
WS -
Data Analysis #5
WS -
Data Analysis #6
WS -
Data Analysis #7
WS -
Data Analysis #8
WS -
Density of a Paper Clip Lab Review
WS -
Dimensional Analysis
WS -
Distinguishing 2nd and 3rd Law Forces
WS -
Force vs Displacement Graphs
WS -
Frames of Reference
WS -
Freebody Diagrams #1
WS -
Freebody Diagrams #2
WS -
Freebody Diagrams #3
WS -
Freebody Diagrams #4
WS -
Graphical Relationships and Curve Fitting
WS -
Indirect Measures
WS -
Introduction to Springs
WS -
Kinematics Along With Work/Energy
WS -
Lab Discussion: Gravitational Field Strength and the Acceleration Due to Gravity
WS -
Lab Discussion: Inertial and Gravitational Mass
WS -
Mastery Review: Introductory Labs
WS -
Metric Conversions #1
WS -
Metric Conversions #2
WS -
Metric Conversions #3
WS -
Metric Conversions #4
WS -
net F = ma
WS -
Practice: Vertical Circular Motion
WS -
Properties of Lines #1
WS -
Properties of Lines #2
WS -
Ropes and Pulleys in Static Equilibrium
WS -
Scientific Notation
WS -
Significant Figures and Scientific Notation
WS -
Standard Model: Particles and Forces
WS -
Static Springs: The Basics
WS -
Vocabulary for Newton's Laws
WS -
Work and Energy Practice: Forces at Angles
TB -
Systems of Bodies (including pulleys)
TB -
Work, Power, Kinetic Energy
TB -
Working with Vectors
TB -
Working with Vectors
REV -
Math Pretest for Physics I
PhysicsLAB
Copyright © 1997-2018
Catharine H. Colwell
All rights reserved.
Application Programmer
Mark Acton