Overview
All work must be shown!!!!!!!!!!!
Linear Motion –Linear Kinetics Lab – Impulse-Momentum
Assignment Goals:
- Review and solidify linear kinetic concepts of impulse & momentum and GRF
- Practice calculating linear kinematics variables from kinetic data
- Practice manipulating impulse to change momentum
Meet Expectations:
⬜ Attend Lab & Participate in lab activities to the best of your abilities
⬜ Complete the assignment in full (Token Opp: Diving Questions OPTIONAL)
⬜ Show all math for calculation questions
Token Opportunities:
⬜ Successfully attenuate your landing GRF, achieving the LOWEST GRF (in Body Weights) in the lab section. (+1 Token for each member of the group)
⬜ +1 Token for each accurate Question Set in Token Opp: Diving Questions
Necessary Submission Tech:
⬜ Completed Lab Assignment File
⬜ Completed GRF Graph file
Lab Overview:
Welcome to the Impulse-Momentum Lab! In this powerful session, you'll explore the fundamental concepts of force application and its effects on motion in biomechanics. Here's what you'll be doing:
• Performing and analyzing a countermovement jump using a force platform
• Investigating different landing techniques and their impact on ground reaction forces
• Examining horizontal impulse generation in different throwing techniques
Through these activities, you'll gain practical experience in data collection, analysis, and interpretation of force-time curves. This lab will help you understand how biomechanists study and optimize human movement in sports, injury prevention, and performance enhancement.
For this lab, you will be using the Impulse-Momentum equation as well as the uniformly accelerated motion equations:
• ∑Ft = m(∆v)
• d = vit + (1/2)at2
• vf = vi + at
• vf2 = vi2 + 2ad
Let's dive into impulse and momentum to discover how forces shape our movements!
Part 1: Countermovement Jump Analysis
Part 1: Instructions
1. One group member will perform a countermovement jump on the force platform.
2. Scale the force platform to the group member's weight and record their body weight in Newtons.
3. Analyze the jump's vertical ground reaction force (GRF) output graph.
Part 1: Data
Body Weight in Newtons: _____
Using your subject’s CMJ document, complete the following tasks. You can find this file in the GRF Data shared Google Drive folder linked on the assignment page on Canvas. It will be labeled “SubjectNameCMJ.txt”.
1. Download the .txt file to your computer
2. Open the Custom GRF Lab Assistant GTP linked on the lab assignment page on Canvas.
3. Attach the file and put “BW in N is [Subjects BW in N]” and click the arrow to run
4. Copy the bulleted data points below.
CMJ Data:
•
Part 1: Tasks
Using your subject’s GRF Graphs document and the data above, complete the following tasks. You can find this file in the GRF Data shared Google Drive folder linked on the assignment page on Canvas. It will be labeled “[Subject Name] GRF Graphs”.
On the CMJ Graph:
1. Label the following points:
a) Start of movement
b) Maximum GRF during propulsive phase (pre-jump)
c) Maximum GRF after landing (post-jump)
d) Start of airborne phase
e) End of airborne phase
2. Shade in the jumping impulse area and label the maximum force (in Newtons and Lbs) at pre-jump.
Part 1: Questions
1. Determine the jump height.
2. Calculate velocity at takeoff.
3. How does the shape of the force-time curve relate to the phases (downward prep, propulsive, airborne, landing) of the jump?
4. What does the area under the curve (impulse) represent, and how does it relate to the jump performance?
5. How might changes in the force-time curve affect jump height? Provide specific examples.
Part 2: Landing Techniques and GRF Attenuation
Part 2: Instructions
1. One group member will perform two landings on the force platform after stepping off a chair:
• First landing – Stiff Landing: Stiff straight leg technique (landing on both feet, bending knees as minimally as possible)
• Second landing – soft landing: Attempt to soften the landing force by adjusting your landing technique.
2. Before the second landing, discuss and strategize methods for softening the landing. The group that reduces their landing impulse to the least amount of body weights will earn a token.
3. Be sure to measure the height of the chair for use in calculations.
Body Weight in Newtons: ___
Height of the chair:
• 19 inches
• _____ m
Using your subject’s Stiff Landing and Soft Landing files, complete the following tasks. You can find these file in the GRF Data shared Google Drive folder linked on the assignment page on Canvas. The stiff landing data will be labeled “SubjectNameStiff.txt” and the soft landing data will be labeled “SubjectNameSoft.txt”
1. Download the .txt file to your computer
2. Open the Custom GRF Lab Assistant GTP linked on the lab assignment page on Canvas.
3. Attach the file and put “BW in N is [Subjects BW in N]” and click the arrow to run
4. Copy the bulleted data points below.
*NOTE: You can only do one file at time.
Stiff Landing Data:
•
Soft Landing Data:
•
Part 2: Tasks
For each landing's GRF Graph:
1. Label the maximum force in Newtons and Lbs.
2. Shade in the landing impulse area.
Part 2: Questions
1. Did your volunteer successfully attenuate their landing impact in the second trial? What mechanisms and technique changes might have aided in softening the landing?
2. Calculate landing velocity for both attempts (show your work).
3. Compare the landing impulse generated between the two techniques. Explain any differences you observe.
4. How do these landing strategies relate to injury prevention in sports or daily activities?
Part 3: Water Balloons
Part 3: Water Balloon Questions
1. What is the determining factor on whether the water balloon breaks or not?
2. What were technique factors important in the best water balloon throws?
1. 3.What were technique factors most important in successfully catching a water balloon?
3. Theoretically, if you could throw a water balloon 25 m, could you catch it? Why?
Token Opp: Diving Impulses
Instructions
As you work through the following questions, you will perform a theoretical analysis of entry impulses between group members following a dive into the water from a diving platform (no spring or bounce).
Please be sure to work through these collaboratively and in order.
Questions
Question Set 1: A 3m Drop
1. Calculate the body weight in kilograms (kg) from the weight in lbs and the height in meters (m) from feet and inches for your group's tallest and shortest member.
o Tallest Member:
▪ Height
▪ Weight
o Shortest Member:
▪ Height
▪ Weight
2. Compare the vertical velocity at entry between these two members if they were to step directly off a 3-m diving platform. Whose velocity is higher, or are they the same? Explain your answer.
3. Calculate each member's vertical velocity at entry into the water.
o Tallest Member:
o Shortest Member:
4. After accurately calculating each member's vertical velocity at entry, reflect on your answer to question 2. Were you correct or incorrect? Explain your response.
Question Set 2: Impulse Coming to Stop
5. Calculate the impulse the tallest member experiences coming to a stop after entering the water.
6. Do you think the shortest member would experience the same, lower, or higher impulse comping to a stop entering the water? Explain your answer.
7. Prove your response to the previous question by calculating the height of the platform needed for the shortest member to experience an identical impulse as the tallest member while coming to a stop after entering the water.
8. After accurately calculating each member's vertical velocity at entry, reflect on your answer to question 6. Were you correct or incorrect? Explain your response.
Question Set 3: Impact Force at Entry
For this question set, assume the tallest group member dove from the 3m platform, while the shortest member dove from the height identified in the previous question set – where both enter the water and experience the same impulse while stopping.
9. Which member will enter the water moving faster? Explain your answer.
10. Which member entered the water with more momentum? Explain your answer.
11. Assuming the shortest member impacts the water in a graceful dive but the tallest member panics and impacts the water in a belly flop, who experienced a greater impact force? Explain your answer. Be sure to consider and explain the contribution of velocity, momentum, and impulse in your answer
Document 2
Linear Motion – Linear Impulse-Momentum Assignment – The Softball
Assignment Goals:
⬜ Review & apply your understanding of the Impulse & Momentum relationship
⬜ Practice Impulse-Momentum calculations
Meet Expectations:
⬜ Complete the assignment in full
⬜ Show all work
⬜ Accurately answer the prompts
Name(s):
Scenario:
A softball player at bat is struck by the ball (0.2kg) from a 29m/s pitch on her lateral epicondyle (the bony part of her elbow).
Part 1: Injury Evaluation – Lateral Epicondyle
a. The Lateral Epicondyle can withstand a maximum compression force of roughly 2640 N of direct impact force before fracture. If the ball comes to a stop in 0.002s, what are the chances of injury? (Determine impact force in both N and Lbs)
Part 2: Injury Evaluation – Proximal forearm
b. If the ball were to hit the fleshy part of the forearm instead, it would come to a stop of 0.06s. This area of the arm can withstand similar compressive forces, what are the chances of injury? (Determine impact force in both N and Lbs)