 # Category: A Level Physics Chapters

## Unit 1 AS Exam Past Papers

If you need the 2009-2011 Papers here they are…

Unit 1 Exam Papers

## Why do thick wires have lower resistance?

This text has come from Furry Elephant so I don’t take credit but it is cool, read and have a think…
Even the most apparently reputable sources of information are sometimes full of misconceptions. The BBC manages to demonstrate several all at the same time with this terrible animation trying to explain why thicker wires have a lower resistance than thin ones.
The main argument is that a thick wire has ’more space’ for the electrons to move around in than a thin wire. But wires are made from atoms – that’s where the free electrons come from. So thicker wires have more atoms and so no more empty space (per cross-sectional area) than thin ones. Another implication of the animation is that the wires are like empty tubes. This suggests that the electrons come from the battery as a sort of source rather than already being there everywhere in the circuit. The final problem is the speed of the electrons. Since the animation shows a longer path for the electrons in the empty thick wire their speed must have increased. In fact, the opposite is the case. Electrons travel slower in thick wires.

For a copper wire (at a given temperature) the speed of the electrons depends only on the voltage across it. Imagine a three-lane road and a single-lane road with cars all going at the same speed. More cars pass per second in the wider road even though the speed is the same. More cars (charges) per second means higher current for a given voltage and so smaller resistance.

Since current is the same around a simple series circuit the charges have to go faster where the wire is thinner. Faster charges mean more interactions with the ionic lattice per second and so higher resistance.

## Exam Past Papers Unit 5 & 5D

Here is a zipped file structure to download to your PC. It contains all the exam questions from AQA for Unit 5 from 2002 to 2010. Remember this includes the legacy or old spec papers from 2002-8 which are very similar.

Turning Points Exam Papers 2002_10

## 6 Forces in Equilibrium

This is a unit where you can really go to town on the problems with the vectors. You must read the specification carefully and make sure that you don’t panic if you can’t do all the problems in the post. I have included lots of vector problems which go 360° where the exam board will tend to stick to 90° only to make it easier. However, I am in the business of teaching vectors in 2D and would say I would be a bad teacher to stop just because the exam board don’t do it. You will need the skills found here if you carry on to a Physics type job later on so why not learn now. Most students say it is really hard at first but then the exam is easy and they get it after a bit of graft!

Also you may find it hard to understand the idea that…

1. A diagonal vector can be split into two parts the horizontal and vertical parts which can be treated separately.
2. Two forces can be added together to make a resultant.
3. An object not moving has a sum of all vertical forces as zero and also all horizontal forces as zero.

If you find this is hard keep going as it will click!

#### Resources

6.1 Vectors and Scalars

6.1 Trig Problems (You must have these trig skills before you start the problems)

Unit_7_Statics_Dynamics_Vectors_1 (Easy problems sheet)

6_1_Wires Example (This is an example of resolving – hanging a picture)

Unit_7_Statics_Dynamics_Vectors_2 (Rock Hard Problems Sheet beyond AS/A2)

6.2 Balanced Forces

6_2_Resultant Forces Problems (quick fun problems – no answers)

72_Practical_Coplanar_Forces (practical proving coplanar forces)

6.3 The principle of moments

6_3_Density_of_Ruler_Prac (Use moments to find out density of ruler)

6.4 More on moments

6_4_Bridge_Crane_Prac (Practical showing support forces)

6_4_Putting_Your_Foot_Down_Extension (Nice but more complex sheet on moments in your feet)

## M13a Introduction to Forces. Part 1 of 4. Weight

Introductory lesson in a series of lessons about force. Provides a brief introduction to the study of forces and then discusses 'weight'. Subsequent parts of the lesson will deal with ...normal reaction, friction and tension/compression.

## 7 On The Move (Motion)

The trick to this unit is simply to do lots of calculations over and over again. Test out what you think, try out the animations and you will be able to do the exam questions. The nuts and bolts are important for every calculation. Try to set up each problem with a diagram and then apply one of the UAM equations. If the problem is setup correctly you cannot go wrong. Don’t try and wing it!

I have now worked out every problem in the test book for this unit and answers are shown below so if you need help then here is a place to start.

#### Resources

7.1 Speed and Velocity

7_1_Problems_svt (Problems sheet)

7_1_Problems_Thrust_SSC_vt (Problems sheet)

7.2 Acceleration

7_2_Practical_Acceleration (worksheet + instructions)

incline plane prac example (PDF Example Practical)

7.3 Motion along a straight line at constant acceleration

7_3_Problems (Problems sheet)

73_HSW_Equations_of_motion (Problems sheet HSW)

7.4 Free fall

74_Practical_Falling

7_4_Dropping_objects_results

74_HSW_Falling_mass

7_4_Gravity Worksheet (Problem Sheet)

7.5 Motion graphs

7_5_Exam_questions (Problem Sheet)

7_5_vta_graphs (Data logging analysis for angles of drop)

7_5_Practice Questions (More Quick Questions)

7.6 More calculations on mot ion along a straight line

7_6_Motion and Forces Exam (Exam Exercise with Example Answers)

7.7/7.8 Projectile Motion 1

77_Extension_Projectiles (HSW Activity)

7_8_Practical Sheet (Projectiles Problem sheet in 2D) ## M12c Projectiles Part 3 of 3

How to deal with basic projectile calculations

## 8 Motion and force

This is a unit which really many find quite difficult. To help yourself out you must learn Newton’s 1st, 2nd and 3rd law of forces. Without this knowledge you cannot succeed in explaining or reasoning out most questions. Also there is a basic principle of coplanar forces producing a resultant and therefore acceleration. It is simple as it is…

Big – Small = Resultant in the Direction of Big!

There is an easy way to remember the laws….

1)     Inertia – “Objects” – don’t want to move but when moving find it difficult to stop

2)   F=ma – or ratio F/m = a which is more appropriate. The acceleration on a fat person is found as the ratio of the force of the push to the mass of the person

3)   Opposites – for every force their is an opposite. Fat person on chair pushing down, chair pushes up to support weight with equal and opposite force.

#### Resources

8.1 Force and acceleration

8_1_Newtons Laws (Help sheet)

8.2 Using F=ma  (or F/m = a)

8.3 Terminal speed

83_Terminal Speed Practical (Worksheet – Advanced Extension)

8_3_Termnial V Results for BB (Excel Results)

https://www.hypertextbook.com/facts/JianHuang.shtml

https://www.passmytheory.co.uk/learningcentre/stoppingdistance.aspx

8.5 Vehicle safety

85_Extension_Vehicle_safety (HSW Worksheet)

85_Practical_Sports Shoe (HSW Worksheet) ## AS_9_2_Pully Explaination.flv

Simple idea of F=ma shows that Big-Small = acceleration in direction of Big.

So F = ma ............... T - mg = ma etc....

## 10 Work, Energy and Power

This work builds upon the Y11 work from Additional Science. You should be able to derive the Kinetic Energy formulae, understand the concept of work done and how that can be expressed as an idea of Power. Also the efficiency of devices and some idea about how to apply that to real situations such as solar cells or power stations. The crux of this unit is to be able to construct calculations in your head without the use of usual formulae from a sheet. The way around this is to write down all the quantities that you know and then physically try and express the problem step by step. Don’t try and jump to the answer as you will get it wrong. Also check out your units carefully and check that match.

10 Work Energy Power

10 Work and Power Student Booklet 10.1 Work and energy

work (Practical Raising Mass)

10.2 Kinetic energy and potential energy

10_2_ke_derivation (Help sheet)

102_Table Tennis Practical (Practical Exp)

10_2_kinetic_animation (Quick Comparison Animation)

Bouncing Ball Practical (Excel Blank sheet)

10.3 Power

https://www.en.wikipedia.org/wiki/Power_(physics)

10.4 Energy and efficiency

104_HSW_the_escalator (HWS Worksheet on Escalators)

10_4_elastic (Practical on Elastic Stored Energy)

10.4 Effciency of a Motor

10. 4 Conservation of Energy Analysis

10.5 Renewable energy

10_5_SOL_A5 (efficiency of solar cells practical)

10_5_SOL_R1 (data sheet for practical)

Results (XLS Example Results)

10_5_solar_size_cost (Real Solar Cell Data Calculator)

10_5_Incident_solar_radiation (Real Solar Cell Data Calculator)

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## 11 Materials

This unit depends on an ability to explain and understand force extensiona and YM graphs. It is one of the easy topics but also easy to drop marks if you don’t learn the graphs. Also take care of your areas and units as mm don’t convert well to m when you square them for an area calculation!

#### Resources

11 Materials  (Main notes)

11 Materials Student Booklet (Activities)

No Answers End Unit quiz (End Topic Quiz)

10.1 Density

https://www.en.wikipedia.org/wiki/Density

10.2 Springs

11_2_Robert Hooke Info

finding k (Excel Results)

10.3 Deformation of solids

11_3_Glass_UTS (Excel Results)

11_3_YM_Wire_Prac (Practical Sheet)

13_3_YM_wire (Excel Results)

11_3_Glass_Properties (Extension Materials)

11_3_YM_metal_rubber (Results and Comparison)

10.4 More about stress and strain

114_Scaling (HSW – Scaling Activity)