Teaching Sequence

Work through this resource material in the following sequence:

15 minutes

Part A: What is a coward punch?

40 minutes

Part B: Calculating the force of a punch

5 minutes

Reflection

Part A: What is a coward punch?

Step 1

Advise the class that today you will be looking at the laws of motion through the lens of a societal issue known as the coward punch. Ask the students if they have heard of this before. Elicit responses to determine the prior knowledge of the class regarding this issue. If students have completed Coward Punch: Introductory Workshop - Years 9 & 10 they should have a sound understanding.

Step 2

If they have not already arrived at it through step 1, give the students the following definition:

A coward punch is a punch made without warning or while the victim is distracted, not allowing for any preparation by the victim.

Let them know that this can be a very dangerous situation for the person who is hit (the victim) and has many negative outcomes for the person who hit them (the perpetrator), as well as having a wider effect on many connected individuals and communities.

Step 3

Play this video:

Consequences of a Coward Punch - Professor Kate Drummond AM (youtu.be/ns05--Bu1So)

After the clip, verbally reinforce that injury comes directly from the punch contact and the ground contact, however, there are many more factors at play including the fragility of the skull, brain tissue and neurological connectors through the neck.

Step 4

Explain that there are several initiatives run by governments and organisations to reduce the frequency of this kind of assault, including the STOP the Coward Punch campaign featuring the champion boxer Danny Green. Show them the following ad for this campaign:

A Coward's Punch Can Kill - Danny Green (https://www.youtube.com/watch?v=ns05--Bu1So)

Step 5

Invite the students to stop and think about the laws of motion at play in an assault of this nature. Ask them to complete the questions on their worksheet to prompt their thinking. The questions being asked of the students are as follows:

Consider what is happening in terms of forces, energy and kinematics (paths of motion). You may use diagrams or formulae in your responses.
What do you think is happening when...

Suggested answers included below:

	Forces	Energy	Kinematics (path of motion)
1 … a person gets hit in the head?	Force from fist (with the mass of the person’s body behind it) is applied directly to the head.	Kinetic energy of fist/body transferred to head/body of victim. The kinetic energy will also be transformed into sound energy and a little thermal energy.	See diagram below. Assume a simple, straight punch without any arcing of the arm or movement of the body.
2 … a person is falling?	Gravitational force pulls the person down.	Kinetic energy from the punch is transformed into gravitational potential energy (briefly) after the punch as the victim teeters on the edge of falling. Gravitational potential energy is transformed into kinetic energy once more as the person falls.	At this level, curved paths of motion are not expected. Assume straight paths of motion. Some students may draw curved paths.
3 … a person’s head hits the ground?	The force of the ground pushing up is applied to the head and balances the gravitational force pulling it down. Depending on the surface type, the upward force will be applied in a very short space of time (as with concrete) or over relatively more time (as with grass or more flexible surfaces). The head may bounce on the surface once or twice due to the upward force being applied to it.	Kinetic energy from the fall is transformed into (some) thermal energy and more sound energy.	The students may or may not add in the path of the head bouncing.

Part B: Calculating the force of a punch

Step 1

Explain to the students that, having looked at coward punches and forces in isolation, you will be investigating how the force of a punch is calculated. Ensure students have access to the website boxingscience.co.uk/science-behind-punch/ or a printed copy of the website along with the videos on the Student Worksheet.

Emphasise to the students that, while this article is written for aspiring boxers, we will be using it to determine formulae and values for our analysis - not training to become boxers. Using this information to hurt someone would be unethical.

Step 2

Have students form groups of three or four. They each have a set of questions on their worksheets for this activity, together with guidance on how to approach the questions. These questions require a somewhat extended process of deduction and may be quite challenging for students at first. They are designed to develop student problem-solving skills around complex questions.

Before they begin, let them know the following:

Answers cannot be found directly on the site; the information on the site will help to inform their thinking and will provide hints and further information for the questions
They should read the whole article first before attempting the questions
They are expected to give detailed and fully explained answers in the final column
You have clues they can ask for to guide their responses (from the table given below).

Step 3

Have the class read the full article first, then complete the first question. Give clues to the whole class over time as they work or to individual table groups when they ask or get stuck.

Step 4

Go over the solution for the first question with the class by reading the solution slowly at least twice, then allowing time for the groups to self-correct and identify what they could have included (or omitted) to make their response more scientifically valid. You may also wish to write the dot point version on the board for them.

Allow time for them to complete the second question, then repeat the process of giving the solution for this question.

Step 5

Have students complete the next part of the worksheet by gathering information from the article then elaborating on these key points. The questions and solutions are outlined below.

Step 6

If possible, arrange your students in a circle or an arrangement in your classroom conducive to inclusive class discussions. Engage the class in a discussion linking what you have found out about the force of a punch and the context of coward punches. Try to use open questions and give ownership of the discussion to the students. Encourage them to build on each other's answers. Below are some sample questions to use:

What did you find out about the forces of punching that you didn’t already know?
Were you surprised by the magnitude of the forces and accelerations in a punch?
Since the year 2000, at least 172 Australians have needlessly lost their lives to the coward punch, with countless more suffering debilitating injury and disability for the rest of their lives. Do you think it was the force of the punch causing these deaths and injuries, or might it be another aspect of the attack?
What form of debilitating injuries and disabilities might be caused by a coward punch? Can you think of any other possible negative side effects from this kind of head trauma?
What are some of the differences between a boxer, or MMA fighter, and someone perpetrating a coward punch?
Suggested answer: Boxing gloves reduce the direct force being applied to the opponent; fighters enter into the situation expecting to be attacked in such a way and can react in such a way to reduce the force being applied to their head and body.
Did you find any applications of the laws of motion that you weren’t expecting?

Worked examples:

<tr">Professional boxers use a technique known as a “snap” to increase their “effective mass”. This in turn increases the impulse delivered to the punch recipient. Use the relevant formulae to explain how this works.

I = Δp
= mΔv
= FΔt

Snap -
body stiffens on impact, mainly arms and torso

• Identify I = mΔv
• Explain how rigidity increases mass
• Link to formulaBy making the arm and torso rigid, the boxer aims to essentially allow this whole part of their body to act as a single object, thus increasing the calculation of mass, thus increasing I as I = mΔv

Question

Brainstorming
Write down all formulae and concepts that come to mind when you read the question.

Dot point response
Try to address each key point in the question using dot points.

Full response
Write a fully worded response to the question.

Think about Newton’s Second Law. What needs to be changed about the boxer and the punch technique in order to change the force of a punch? Explain how changing each variable increases or decreases punch force.

Note: An answer relating to strength is not sufficient!

F = ma
How to change F
Change a, a = Δv/t
Change m

• State F = ma
• Identify a and m as relevant variables
• Explain how to change a
• Explain how to change m

Newton’s Second Law is F=ma. Since we are looking for a change in F, m and a are the variables that could change. Since a = v/t, to increase we would need to decrease the time taken for the punch to reach hitting speed, or 'throw the punch faster'. m is the mass, which is related to the mass of the boxer, meaning the more 'weight we throw behind' a punch the more force it will deliver by the technique of throwing the body and by increasing body mass.

Professional boxers use a technique known as a 'snap' to increase their 'effective mass'. This in turn increases the impulse delivered to the punch recipient. Use the relevant formulae to explain how this works.

I = Δp
= mΔv
= FΔt
Snap -
body stiffens on impact, mainly arms and torso

• Identify I = mΔv
• Explain how rigidity increases mass
• Link to formula

By making the arm and torso rigid, the boxer aims to essentially allow this whole part of their body to act as a single object, thus increasing the calculation of mass, thus increasing I as I = mΔv

How many newtons of force is typical for an amateur boxer? 2500 N

For a 70kg typical amateur boxer, what is the approximate value of ? 3.5 (3.571 with g = 10 ms^-2 - rounded to 3.5 in article)

Explain what is meant by 'the elephant and the rocket' analogy from the article in terms of momentum.
Since p=mv, to increase momentum we must increase mass or velocity. In the case of an elephant, it is very massive but not very fast. For a rocket, it is very fast but not very massive. It is possible, with certain values, to have both of these reach the same momentum.

Reflection

Invite students to complete a connect , extend, challenge exercise on the Student Worksheet.

Differentiated learning

Extension

This reference material is a guide to the mathematics of simple kinematics written for teachers. It contains examples, questions and solutions along with good explanations similar to a student textbook. Content from pages 6 - 26 is suitable for Year 10 students and will provide a good foundation for skills should they enter VCE Physics later on. From page 17 is the straight-line motion equations content which can be applied to today’s context using values from Part B.

Provisions for learning support

Part B: Consider grouping students based on diverse abilities or remove some of the questions to allow for time to focus more deeply on one aspect. This part could also be conducted in a flipped learning style.

Teacher reflection

Take this opportunity to reflect on your own teaching:

What did you learn about your teaching practice today?
What worked well?
What didn't work so well?
What would you share?
Where to next?
How are you going to get there?

Coward Punch - Calculating the Force of a Punch

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