Teaching Sequence

Work through this resource material in the following sequence:

15 minutes

Tune In What is a coward punch?

20 minutes

Find Out: Identifying and representing forces

40 minutes

Take Action: Considering the consequences of coward punches

5 minutes

Reflection

Tune In: What is a coward punch?

Step 1

Advise the class that today you will be looking at forces 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 7 & 8 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.

The following activity may be triggering for some students. Consider your group before using it with your class. You may like to offer permission for students to leave the room if they feel this is too much for them, or to manage their emotions in whatever way they need to.

Step 3

To get the students on the same page about the coward punch context and negative outcomes, show them the following video:

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

Allow some time for students to debrief and discuss the content of the video, focusing particularly on what a deceleration injury is and the devastating effects of such an injury.

Find Out: Identifying and representing forces

Step 1

Explain to students that, before examining the forces involved with a coward punch, we need to familiarise ourselves with drawing free-body diagrams. We use these diagrams to show the forces acting upon an object using arrows to represent the direction and size of the force, where the length of the arrow is how strong the force is and the direction in which the force is pushing or pulling. At this level, it is sufficient to draw free-body diagrams using a simple shape to represent objects (usually a box) and draw all forces from the centre of the shape.

Understanding the importance of arrow length in free-body diagrams is critical to understanding the direction in which an object is moving. There can be multiple forces pushing or pulling an object in different directions. The key to understanding the overall direction of movement is by recognising which of the arrows is longer than the other: the object will move in the direction of the longest arrow, as well as changing velocity (speed in a given direction).

Example: In the questions below, the example of a skydiver accelerating (speeding up) in freefall is given: the arrow representing gravity is longer than the arrow representing friction caused by the air resistance. This means the skydiver will be accelerating in the direction of the greater force. Where arrows are of equal length, it means that the object is either not moving (physicists would say "at rest") or moving at a constant speed. Balanced forces and the effect of these on the movement of objects is Newton’s First Law of Motion in action (source).

Step 2

Show the following video (from the beginning, then pausing at 4:32) to explain the concept of free body diagrams, types of forces and the first example of how to draw these:

Drawing Free-Body Diagrams With Examples (youtu.be/3rZR7FSSidc) - pause at 4:32

Step 3

Pause the video after the explanation of the example one solution (4:32) and give the students ample time to copy down the correct answer for example one, as well as attempt question two. Once they have attempted question two, play the solution, then pause again and so on until all six questions have been completed.

Depending on the class, you may wish instead to give them time to complete all questions, then play all solutions afterwards. Here are the questions and solutions for you:

Step 4

Explain to the class that now that you’ve looked at some more common applications of drawing free-body diagrams, you’re now going to look at using the same process to explore forces through the lens of the coward punch. Invite students to attempt a free-body diagram of a person being struck in the head with a fist, also on their worksheet.

Learning support: For any students challenged by the idea, ask them to consider what forces might be at play in the scenario and, once they’ve guessed at the forces, to consider the direction in which those forces will cause the free body (i.e. the head) to move. You can use more prompting questions to scaffold this for students with questions such as:

If someone is hit, what is hitting them? What direction would that cause the head to move?
When someone is hit, what is likely to happen to them? If they fall down, what force is causing them to fall?
(Following from the last question) If gravity is what causes us to fall, what is stopping gravity from pulling us down to the ground while we’re walking around? What keeps our heads up and looking forward?

Step 5

To answer this one, explain that we have gravity acting downwards, the force of the neck on the head acting upwards (and the force of the fist acting sideways). Explain that because the sideways force is unbalanced, the person’s head will accelerate sideways, causing the person to be knocked over, and if this person can’t catch themselves (e.g. if they trip or they are unconscious), they will fall.

Proposed answer:

If students are finding the idea of the neck exerting a force upwards challenging, ask them to consider what else would be holding our heads up if gravity is always pulling objects down. We’re all familiar with the concept of 'what goes up must come down' but we don’t often think about what it means for objects to not fall all the time - there must be something holding them up! In the case of our heads, that’s our neck (the bones and the muscles). This same logic applies to just about everything else that doesn’t succumb to gravity; if an object isn’t falling, then there’s a force pushing against gravity to hold it in place. And if that object isn’t moving, then the forces must be balanced.

Take Action: Considering the consequences of coward punches

Step 1

Lead a class discussion around why hits to unexpectant victims may cause more damage than a hit to a person who is expecting it. Ask the students to refer to forces in their responses.

Examples include:

If prepared, the victim may duck or get out of the way and not be hit (no force on the head from the fist)
If prepared, the victim may put up their arms to protect their head (force applied to arms, protecting vital organs)
If prepared, the victim may turn their head, so the fist glances off (lower force on the head)
If prepared, the victim or bystander may be able to lower aggression in the perpetrator and avoid a hit entirely, meaning no new forces are being applied to the head.

Discuss the possible consequences of being hit in the head, both for the victim and the perpetrator.

Examples include:

Physical injury (victim: head, brain, death; perpetrator: hand, wrist, arm)
Emotional injury (victim’s fear, anxiety; bystanders; families of both victim and perpetrator)
Legal consequences (perpetrator: fine, incarceration, community service)
Economic damage (victim: injuries leading to physical impairment are likely to prevent them from being able to work in the same capacity/at all depending on the nature of the impairment, mental anguish might affect their mood, personality and coping mechanisms for partaking in ‘normal’ life; perpetrator: in addition to fines, prison sentences and a criminal record may cause inability to work in the same capacity).

Be sure to emphasise that there is no positive outcome to the coward punch.

Step 2

Inform students that in the next lesson, they will be looking at what happens to a person after the punch by dropping different balls onto different surfaces to model the effect of hitting one’s head on the ground.

Reflection

Ask students to offer insight on what they learned and revised today. This will hopefully include identifying and drawing forces:

What is a coward punch and why is it bad?
How a coward punch looks in terms of forces.

Ask students what today’s lesson made them wonder about and what else they want to learn about these topics. There are prompts on the Student Worksheet if you want them to record these thoughts.

Differentiated learning

Extension

Part C: This section also lends itself to the investigation of Newton’s Third Law. Use this 5-minute video to introduce or reinforce the concept.
Use the same questions from Part C to talk about the reactionary forces for each of the forces described. To do this, simply reverse the objects in each F of on _ statement. E.g. Fgrav is the force of the Earth on the object, so the reactionary force is the force of the object on the Earth. Reactionary forces are of the same type (gravitational, applied/contact, magnetic, etc.), equal in magnitude and act in the opposite direction to the original force.

Provisions for learning support

Part A: Issue this activity as a flipped learning style task in advance of the lesson for students who may need to watch the videos multiple times to interpret meaning.
Part B: On separate devices, allow students to move through the task at their own pace rather than using a whole class approach.
Part C: Limit the number of questions for students, and consider the grouping of students based on diverse abilities.

Coward Punch - Representing Forces

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