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Physics Industry Related Resources

Momentum & Collisions

Topic

Summary

Resources

Specifications

Lesson 1

Crash Barriers

Introduction to crash barriers and key facts

Teachers Notes

PowerPoint

Edexcel P3 3.22 Collisions

OCR Gateway P3 Forces for Transport

GCSE 21st Century Science Physics Unit 4 Explaining Motion

Lesson 2

Crash Barriers

Crash barriers investigation Practical Activity: investigate different variables in order to decide on cost effective specifications for a barrier in a given location.

Teachers Notes

Worksheet 1 - 4 different worksheets (one per group) investigating different variables

Lesson 3

Crash Barriers

Advisory Conference

Students complete an Experts Report with their findings.

Students then feedback their findings with a student from each of the other 3 groups and form an Advisory Panel.

Peer and Self Assessments

Teachers Notes

Experts Report

Crash Barrier Advisory Panel

Peer Assessment

Self Assessment

Lesson 1 Crash Barriers: Teacher and Technician Notes

Outline of the Lesson

In this lesson, pupils are introduced to the topic of crash barriers. The PowerPoint presentation can be used in this lesson.

A good starter would be showing a clip showing crash barrier testing from YouTube (there are lots to choose from!)

Pupils then discuss what they already know about crash barriers - what they are, where they are used and how they work. Some key points that all pupils should be aware of following this discussion:

Crash barriers keep vehicles within their roadway and prevent vehicles from colliding with obstacles such as walls, large road signs and boulders or from leaving the road and entering deep water or travelling down very steep slopes.

Crash barriers are also installed within the medians of divided highways to prevent vehicles entering opposing carriageways. There barriers are designed to be struck from both sides.

Barriers are normally designed to minimise injury to vehicle occupants, but injuries do occur in collisions with crash barriers. They should therefore only be installed where a collision with the barrier is likely to be less severe than a collision with the hazard behind it.

There are different types of crash barriers. Flexible barriers (which will be modelled in this investigation) will deflect 1.6 metres (5.2ft) to 2.6 metres (8.5ft) when struck by a typical passenger car or light truck. Impact energy is dissipated in a number of ways including through deformation of the rail elements and posts, deformation of the impact vehicle bodywork, and friction between the rail and vehicle.

Essentially, crash barriers work by slowing the vehicle over a longer time, therefore decreasing the impact force (due to force = change in momentum/impact time)

Pupils then consider variables that could affect the outcome of a crash with a crash barrier, leading into an introduction to next lessons investigation.

Variables they may mention include:

Mass of vehicle

Speed of vehicle

Angle of impact of vehicle

Shape of vehicle

Height of crash barrier

Shape of crash barrier

Spacing between posts of crash barrier

Material crash barrier is made from

Introduction to main investigation

The equipment that the pupils will be using next lesson to model the crash barrier impacts is then demonstrated. Pupils should be encouraged to think about what observations they will make of the impact.

Four variables will be investigated:

Momentum of vehicle

Impact angle of vehicle

Height of barrier

Spacing between posts of barrier

Equipment (for demo)

Ramp

Dynamics trolley

corrugated card strip: 6 cm wide and about 50 cm long

Cocktail sticks (about 30)

Scissors

30cm ruler

Substantial strip of plasticine (about half a block when bought new)

Diagram of barrier

(Corrugated cardCocktail stickPlasticine)

The barrier is very quickly made from a strip of corrugated card. It is supported by cocktail sticks inserted at regular intervals. These are embedded in a thick strip of plasticine pressed firmly onto a desk.

(RampDynamics trolleyBarrierCocktail sticksPile of books)Experimental Set Up (not to scale)

If there is time in this lesson, pupils could then be put into the groups they will be working in for the investigation and start preparing for this (e.g. making their model crash barriers/ drawing up tables for results etc)

Lesson 2 Crash Barriers Investigation: Teacher and Technician Notes

Outline of the Investigation

A dynamics trolley is run down a ramp and into a crash barrier at an angle. Both the amount of energy that the barrier absorbs from the trolley and the deformation of the barrier are measured.

Four independent variables are investigated for their effect on the two dependent variables stated above. These are: the height of the barrier; the separation of the struts supporting the barrier; the angle of impact; and the momentum of the trolley. These factors mimic some key considerations in the specification of real life crash barriers and are easily quantifiable in the laboratory.

To take measurements the class needs to be divided into four sets or groups. Each set investigates a different independent variable and collects a set of measurements covering a good range of values.

In the next lesson one person from each set will share their findings with those from other sets completing different investigations. These experts will use their combined knowledge and findings to decide on cost effective specifications for a barrier in a given location.

Equipment (per group)

For height of barrier:

Ramp

Dynamics trolley

2 or 3 corrugated card strips: 6 cm wide and about 50 cm long

Cocktail sticks (about 30)

Scissors

30cm ruler

Substantial strip of plasticine (about half a block when bought new)

For spacing of struts:

Ramp

Dynamics trolley

Corrugated card strip: 4 cm wide and about 50 cm long

Cocktail sticks (about 30)

Scissors

30cm ruler

Substantial strip of plasticine (about half a block when bought new)

For angle of impact:

Ramp

Dynamics trolley

Corrugated card strip: 4 cm wide and about 50 cm long

Cocktail sticks (about 30)

Scissors

30cm ruler

Protractor

Substantial strip of plasticine (about half a block when bought new)

For momentum:

Ramp

Dynamics trollies (to combine for different masses or masses to add)

Motion sensor (any suitable data-logger to measure speed of trolley leaving the ramp)

Corrugated card strip: 4 cm wide and about 50 cm long

Cocktail sticks (about 30)

Scissors

30cm ruler

Substantial strip of plasticine (about half a block when bought new)

Diagram of barrier

(Corrugated cardCocktail stickPlasticine)

The barrier is very quickly made from a strip of corrugated card. It is supported by cocktail sticks inserted at regular intervals. These are embedded in a thick strip of plasticine pressed firmly onto a desk.

(RampDynamics trolleyBarrierCocktail sticksPile of books)Experimental Set Up (not to scale)

Procedure:

In this lesson each group takes measurements for one of the four independent variables. Equal numbers of groups need to take measurements for each variable, so when evidence is considered next lesson new groups can be formed consisting of four students each of whom have completed a different investigation.

Set up the equipment as shown in the plan above.

The cocktail sticks shown are inserted between the top two books in a small pile. They are perpendicular to the barrier and touching it. On impact they will be pushed backwards and the friction between the books will hold them at their maximum deflection. N.B. Lining these sticks up with a strut in the barrier reduces sideways deflection to a minimum.

Before starting a felt pen or pencil can be used to mark the point on each cocktail stick at which it emerges from the pile of books. After collision a second line is marked before the sticks are removed and the length of the gap between the marks records the maximum deflection of the barrier at each position.

The trolley is allowed to accelerate down the slope and into the barrier.

The number of cocktail stick struts that have broken is recorded. This is a rough measure of the amount of energy that the barrier has absorbed from the trolley.

(Energy not absorbed is retained as kinetic energy, meaning the trolley bounces off at a higher speed. The change of momentum, and therefore the force on the trolley, is greater too. Additionally, the breaking of struts increases the time the trolley is in contact with the barrier and further reduces the rate of change of momentum and the forces of impact.)

The maximum deflection of the barrier is measured.

Depending on the specific investigation the independent variable is also recorded. For change of momentum, suitable speed and mass measurements need also to be taken.

Measurements are repeated to cover a good range for each independent variable.

How does the height of a crash barrier affect its properties?

Worksheet 1

Outline of the Investigation

Your task is to investigate one property of a crash barrier to find out how this affects how well it works. Other groups will investigate different properties. Next lesson you will share your information to decide what barrier is needed for a situation you will be given. It is essential that you measure a good range of results that accurately describe what happens.

You will measure two properties of the crash barrier.

How much the barrier deforms, or moves back

Sometimes a barrier needs to protect things behind it and sometimes it only needs to protect the people and vehicles crashing into it

How well it absorbs energy, by counting the number of struts that break in a collision

More struts broken = more energy is taken out of the vehicle and it is safer

Equipment

Ramp

Dynamics trolley

2 or 3 corrugated card strips: 6 cm wide and about 50 cm long

Cocktail sticks (about 30)

Scissors

30cm ruler

Substantial strip of plasticine

Diagram of barrier

(Height) (Corrugated cardCocktail stickPlasticine)

Experimental Set Up (not to scale)

Method

Set up the equipment as shown in the plan above.

The cocktail sticks shown are inserted between the top two books in a small pile. They are perpendicular (90o) to the barrier and touching it. On impact they will be pushed backwards and the friction between the books will hold them at their maximum deflection. N.B. Lining these sticks up with a strut in the barrier reduces sideways deflection to a minimum.

Before starting, use a felt pen or pencil to mark the point on each cocktail stick at which it touches the pile of books.

Roll the trolley down the slope and into the barrier.

After collision, mark a second point on each cocktail stick at which it now touches the pile of books.

Remove the sticks and measure the biggest distance between the marks on the cocktail sticks. This is equal to the biggest backwards movement of the barrier.

Count the number of cocktail stick struts that have broken.

Record your measurement in a table.

Change the height of your barrier and repeat your measurements.

For a good range of results use heights between 2cm and 6cm.

How does the spacing of struts affect the impact on a crash barrier?

Outline of the Investigation

Your task is to investigate one property of a crash barrier to find out how this affects how well it works. Other groups will investigate different properties. Next lesson you will share your information to decide what barrier is needed for a situation you will be given. It is essential that you measure a good range of results that accurately describe what happens.

You will measure two properties of the crash barrier.

How much the barrier deforms, or moves back

Sometimes a barrier needs to protect things behind it and sometimes it only needs to protect the people and vehicles crashing into it

How well it absorbs energy, by counting the number of struts that break in a collision

More struts broken; more energy is taken out of the vehicle and it is safer

Equipment

Ramp

Dynamics trolley

Strip of corrugated card: 4 cm wide and about 50 cm long

Cocktail sticks (about 30)

30cm ruler

Substantial strip of plasticine

(Spacing of struts)

Diagram of barrier

(Corrugated cardCocktail stickPlasticine)

(RampDynamics trolleyBarrierCocktail sticksPile of books)Experimental Set Up (not to scale)

Method

Set up the equipment as shown in the plan above.

Measure the spacing of the cocktail sticks (struts) in your barrier.

The cocktail sticks shown are inserted between the top two books in a small pile. They are perpendicular (90o) to the barrier and touching it. On impact they will be pushed backwards and the friction between the books will hold them at their maximum deflection. N.B. Lining these sticks up with a strut in the barrier reduces sideways deflection to a minimum.

Before starting use a felt pen or pencil to mark the point on each cocktail stick at which it touches the pile of books.

Roll the trolley down the slope and into the barrier.

After collision, mark a second point on each cocktail stick at which it now touches the pile of books.

Remove the sticks and measure the biggest distance between the marks on the cocktail sticks. This is equal to the biggest backwards movement of the barrier.

Count the number of cocktail stick struts that have broken.

Record your measurement in a table.

Change the spacing of the struts in your barrier and repeat your measurements.

For a good range of results use spacings of between 2cm and 6cm.

If you have time increase the range.

How does the angle of impact affect the impact on a crash barrier?

Outline of the Investigation

Your task is to investigate one property of a crash barrier to find out how this affects how well it works. Other groups will investigate different properties. Next lesson you will share your information to decide what barrier is needed for a situation you will be given. It is essential that you measure a good range of results that accurately describe what happens.

You will measure two properties of the crash barrier.

How much the barrier deforms, or moves back

Sometimes a barrier needs to protect things behind it and sometimes it only needs to protect the people and vehicles crashing into it

How well it absorbs energy, by counting the number of struts that break in a collision

More struts broken; more energy is taken out of the vehicle and it is safer

Equipment

Ramp

Dynamics trolley

Strip of corrugated card: 4 cm wide and about 50 cm long

Cocktail sticks (about 30)

Protractor

30cm ruler

Substantial strip of plasticine

Diagram of barrier

(Corrugated cardCocktail stickPlasticine)

(Angle of impact)

(RampDynamics trolleyBarrierCocktail sticksPile of books)Experimental Set Up (not to scale)

Method

Set up the equipment as shown in the plan above.

Measure the angle of impact with a protractor.

The cocktail sticks shown are inserted between the top two books in a small pile. They are perpendicular (90o) to the barrier and touching it. On impact they will be pushed backwards and the friction between the books will hold them at their maximum deflection. N.B. Lining these sticks up with a strut in the barrier reduces sideways deflection to a minimum.

Before starting use a felt pen or pencil to mark the point on each cocktail stick at which it touches the pile of books.

Roll the trolley down the slope and into the barrier.

After collision, mark a second point on each cocktail stick at which it now touches the pile of books.

Remove the sticks and measure the biggest distance between the marks on the cocktail sticks. This is equal to the biggest backwards movement of the barrier.

Count the number of cocktail stick struts that have broken.

Record your measurement in a table.

Change the angle of impact by turning your barrier and repeat your measurements.

For a good range of results use angles of between 15o and 90o.

How does the momentum of a vehicle affect the impact on a crash barrier?

Outline of the Investigation

Your task is to investigate one property of a crash barrier to find out how this affects how well it works. Other groups will investigate different properties. Next lesson you will share your information to decide what barrier is needed for a situation you will be given. It is essential that you measure a good range of results that accurately describe what happens.

You will measure two properties of the crash barrier.

How much the barrier deforms, or moves back

Sometimes a barrier needs to protect things behind it and sometimes it only needs to protect the people and vehicles crashing into it

How well it absorbs energy, by counting the number of struts that break in a collision

More struts broken; more energy is taken out of the vehicle and it is safer

Equipment

Ramp

Dynamics trolley

Strip of corrugated card: 4 cm wide and about 50 cm long

Cocktail sticks (about 30)

Motion sensor

Scales

30cm ruler

Substantial strip of plasticine

Diagram of barrier

(Angle of impact) (Corrugated cardCocktail stickPlasticine)

(RampRampDynamics trolleyDynamics trolleyBarrierBarrierCocktail sticksCocktail sticksPile of booksPile of books)Experimental Set Up (not to scale)

Method

Set up the equipment as shown in the plan above.

Set up a motion sensor to measure the speed of impact.

Measure the mass of your trolley.

The cocktail sticks shown are inserted between the top two books in a small pile. They are perpendicular (90o) to the barrier and touching it. On impact they will be pushed backwards and the friction between the books will hold them at their maximum deflection. N.B. Lining these sticks up with a strut in the barrier reduces sideways deflection to a minimum.

Before starting use a felt pen or pencil to mark the point on each cocktail stick at which it touches the pile of books.

Roll the trolley down the slope and into the barrier.

Record the speed of your trolley.

Record the momentum of your trolley (= mass x speed).

After collision, mark a second point on each cocktail stick at which it now touches the pile of books.

Remove the sticks and measure the biggest distance between the marks on the cocktail sticks. This is equal to the biggest backwards movement of the barrier.

Count the number of cocktail stick struts that have broken.

Record your measurement in a table.

Change the momentum of your trolley: either add mass or change the height of your ramp.

For a good range of results make the biggest momentum four times bigger than the smallest.

Lesson 3 Crash Barriers Advisory Conference: Teacher Notes

Outline of the Conference

This is the concluding lesson of this unit of work. During the investigation, the class was divided into four with each set investigating a different independent variable. Each pupil has become an expert in a specific field of research and they will now combine with one pupil from the three other experimental sets to form an advisory panel. Working collaboratively, the panel will apply their combined knowledge and findings to decide on cost effective specifications for a barrier in a given location. Their decisions and justifications are presented at a poster conference.

Suggested Format

Before forming their advisory committees, pupils should be given time to work with their fellow experts to complete an experts report. The report will provide each pupil with a brief summary of their investigation. A report template could be provided and should gather information based on suitable questions like what were we finding out, what did we do, what have we found out and what evidence do we have to justify our conclusions.

Upon forming their advisory committees, pupils communicate their findings to the other experts of different fields. So that they can fully engage with group discussions, it is important that all members of the advisory committee have an overview of all of the experimental results. It is therefore suggested that a) as expert reports the remaining panel members complete the information collection sheet and b) the contextual situation should only be revealed to a group once all members have reported to the panel.

Through group discussion, each advisory panel decides on the cost effective specifications for a barrier in a given location.

The advisory panels create a professional poster that portrays the design of their barrier and the scientific reasons behind it. The class could create their own success criteria from which the posters will be assessed. Example success criterion categories could include design and chose of materials; cost effectiveness; the use of scientific evidence to justify the design.

Finally, in the format of a professional poster conference, each panel will pitch and justify their contextual barrier design. Peer, self and teacher assessment could be utilised here.

Equipment (per pupil)

Experts Report form

Peer assessment form

Self assessment form

Equipment (per advisory panel)

Poster making equipment e.g. A2 paper, pens, pencils, lined paper, graph paper, rulers etc...

Information collection sheet

(Delivered in partnership with the Department for Education)

(Crash Barrier Advisory PanelHow does the height of the barrier affect its properties?How does the spacing of struts affect the impact on a crash barrier? How does the angle of impact affect the impact on a crash barrier? How does the momentum of a vehicle affect the impact on a crash barrier? )

Experts report

You have investigated how one property of a crash barrier affects its ability to work, and are now an expert in this field. Answer the questions on this worksheet to create a report that summarises your findings. You will use these notes to communicate your conclusions to a panel of crash barrier advisors.

1) What were you finding out?

2) Briefly describe what you did to test your given property.

3) Analyse your results and describe what we have found out.

4) What evidence do we have to justify our conclusions?

5) Critically evaluate your procedure and state whether or not your results are creditable (are they fair, accurate and reliable)? If so explain why. If not, explain why.

Peer Assessment

Success Criteria:

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

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Strengths

Heres what you are doing effectively: well done!

______________________________________________________

______________________________________________________

______________________________________________________

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Targets

Please work on these areas in order to develop your skills:

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

__________________________________________________________________

This work was peer assessed by _______________________________________

Self Assessment

Success Criteria:

_______________________________________________________________

__________________________________________________________________

_______________________________________________________________

__________________________________________________________________

_______________________________________________________________

__________________________________________________________________

Strengths

Heres what I am doing effectively!

_______________________________________________________________

__________________________________________________________________

_______________________________________________________________

__________________________________________________________________

Targets

I will now work on these areas in order to develop my skills:

_______________________________________________________________

__________________________________________________________________

_______________________________________________________________

__________________________________________________________________

(Delivered in partnership with the Department for Education)