FORCES AND THEIR EFFECTS

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FORCES AND THEIR EFFECTS

• Unit 7K
• Year 7 Science

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(No Transcript)
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Index
introduction lesson 1 Are some magnets stronger
than others? lesson 2 What forces act on a
parachute? Homework task 2 lesson 3 How much do
balls bounce? lesson 4 Do rollers make it easier
to drag heavy things? lesson 5 Why is iron
heavier than aluminium? lesson 6 Are objects
lighter under water? lesson 7 Why are some toy
cars faster than others? lesson 8 Do things
float better in salty water? lesson 9 Is
friction sometimes useful? lesson 10 Do pulleys
help with lifting?
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Forces

• What are forces?
• How do we measure forces?
• How do we use forces in our ordinary lives?
• How do forces affect our lives?

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What do all these terms mean?

• FORCE the influence that produces a change in a
  physical quantity "force equals mass times
  acceleration" (Newtons)
• POWER the rate of doing work measured in watts
  (joules per second)
• WORK "work equals force times distance"
• ENERGY the capacity of a physical system to do
  work (joules)

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Introduction
Getting help
You will be loaned a study guide
Use our web site
This unit is all about FORCES pushes, pulls and
twists Forces are measured in NEWTONS
http//www.westwightmiddle.iow.sch.uk/science.htm
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Lesson 1

• Are some magnets stronger than others?

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Objectives and what I am looking for

• Learn about magnetic force
• Learn to list the key variables effectively
• Learn to evaluate the way you work
• Make careful measurements.

• Learn how to use the guide mats
• Make a proper variables list
• Record your results in a table

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Equipment

• A variety of different magnets
• 30 cm rules marked in mm
• Steel ball bearings
• Results tables
• Level mats
• Study guides (3 levels differentiated)

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Are some magnets stronger than others?
Learn to list the key variables effectively Learn
to evaluate the way you work Make careful
measurements.

• Watch a demonstration of how to test.
• What are variables?
• Use whiteboards to list the variables.

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Are some magnets stronger than others?
Learn to list the key variables effectively Learn
to evaluate the way you work Make careful
measurements.
New page. Date and title in your book.

• Planning
• Make a list of the key variables
• Which variable will you test?
• Which variable will you measure?
• Which variables will you keep the same?

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Are some magnets stronger than others?
Learn to list the key variables effectively Learn
to evaluate the way you work Make careful
measurements.

• Put the ball bearing on the table.
• Move the magnet nearer to the ball bearing.
• How close was the magnet when the ball started to
  move? Measure.
• Record your results and try again with a
  different magnet.

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Are some magnets stronger than others?
Learn to list the key variables effectively Learn
to evaluate the way you work Make careful
measurements.
Lets share our results
Observations State which magnet is the strongest
according to your results.
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Are some magnets stronger than others?
Learn to list the key variables effectively Learn
to evaluate the way you work Make careful
measurements.

• Evaluation
• How well did your test go?
• Did you feel that your results were accurate?
• How could you have improved your test in order to
  get more accurate results or results you could
  have been more sure of?

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Lesson 2

• What forces act on a parachute?

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What forces act on a parachute?
Parachute video (it might work)
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Equipment

• Digital camera
• A football
• Parachutes
• Timers
• Whiteboards, pens erasers
• Study guides (3 levels differentiated)

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OBJECTIVES what I am looking for

• To learn about a force called DRAG
• To learn to draw force diagrams
• To learn how to mark forces on a diagram

• Make a diagram that clearly shows the forces that
  act on it.
• Write to describe which force is largest.
• Write to explain how you know.

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How to mark force arrows on diagrams.
To learn about a force called DRAG To learn to
draw force diagrams To learn how to mark forces
on a diagram
lift
drag
thrust
New page, date title. Copy the diagram.
weight
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Football
To learn about a force called DRAG To learn to
draw force diagrams To learn how to mark forces
on a diagram

• We will go into the playground to watch a
  football and bring back a photograph.

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Football photograph

• Trim and fix the photograph into your book.
• Use arrows and straight lines to mark
• Gravity
• Drag

To learn about a force called DRAG To learn to
draw force diagrams To learn how to mark forces
on a diagram
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Next bit

• DVD video input BBC Class clips

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Plenary What forces act on a parachute?
To learn about a force called DRAG To learn to
draw force diagrams To learn how to mark forces
on a diagram
HOMEWORK

• Try a parachute in the lab from a height of
  exactly 2 metres.
• NOW RECORD THIS ON YOUR GROUPS WHITEBOARD
• Decide what force pulls the parachute down.
• Decide what force holds the parachute up.
• Which of the forces was greatest? Explain how you
  know.

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What forces act on a parachute?
To learn about a force called DRAG To learn to
draw force diagrams To learn how to mark forces
on a diagram
IN YOUR BOOK

• The force that pulls the parachute down is
• The force that holds the parachute up is.
• Draw an accurate 2d diagram that shows the
  parachute and the two forces acting on it.
• The force that was greatest was I know this
  because

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Finishing up

• Forces Hammer Feather on the Moon. (Class
  Clips DVD)

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Homework task 2

• Use your knowledge of DRAG to explain why sports
  cars are streamlined.

HOMEWOK SHEET
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Use your knowledge of DRAG to explain why sports
cars are streamlined.
Use your knowledge of DRAG to explain why sports
cars are streamlined.
Use your knowledge of DRAG to explain why sports
cars are streamlined.
Use your knowledge of DRAG to explain why sports
cars are streamlined.
Use your knowledge of DRAG to explain why sports
cars are streamlined.
Use your knowledge of DRAG to explain why sports
cars are streamlined.
Use your knowledge of DRAG to explain why sports
cars are streamlined.
Use your knowledge of DRAG to explain why sports
cars are streamlined.
Use your knowledge of DRAG to explain why sports
cars are streamlined.
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Lesson 3

• How much do balls bounce?

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Getting started

• Draw a ball falling. Think about its shape.
• Draw a ball that has hit the ground and is about
  to bounce back up. Think about its shape.

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OBJECTIVES what I am looking for

• How do forces make things bounce?
• Are my measurements accurate?
• Why is it important to repeat my tests?
• How can I use my scientific knowledge to explain?

• Be able to do a test and make accurate
  measurements.
• Be able to repeat measurements to check.
• Be able to clearly describe what happened.
• Be able to use your knowledge to explain how and
  why things happen.

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Which forces make balls bounce?
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Equipment

• Clamp stand with clamp and boss.
• Metre rule.
• Table tennis ball.
• Results table.
• Study guides.

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Results
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Conclusion

• According to your results, describe what
  happened.
• Use your understanding to explain why the first
  bounce was more than the second bounce.

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Something to think about

• The falling ball had kinetic energy because it
  was moving.
• The amount of movement got less after the first
  bounce.
• So, where did the kinetic energy go?

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Plenary finishing off

• Your group might be asked to read your
  conclusion.
• Copy your conclusion to your exercise book.
  Improve it as you go.
• Homework Complete the conclusion in your book.

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Forces their effects Lesson 4

• Do rollers make it easier to drag heavy things?

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Just for starters

• Draw a picture of a bloke dragging a heavy rock.
• Draw a picture of the same bloke dragging a heavy
  rock using rollers.

• Can you show which one is the hardest work?

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OBJECTIVES what I am looking for

• To learn how to write why your test is fair.
• To learn how to make a useful bar chart.
• To extend your ability to explain why things
  happen.

• Know about control, independent and dependent
  variables.
• Write a useful prediction.
• Record your results accurately.
• Write to explain why things happened.
• Write an evaluation.

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Equipment

• FOR GROUP WORK
• Dowel rollers
• Force meters
• String
• A brick
• Study guiders
• Results tables
• Level mats

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Key variables

• INDEPENDENT VARIABLE
• The variable I will test is
• DEPENDENT VARIABLE
• The variable I will measure is
• CONTROL VARIABLES
• The variables I will keep the same are

Redraft into your exercise book.
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Practical bit
RESULTS
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Conclusion

• Produce a graph that shows these results clearly.
  What should my graph look like?
• Write to explain what happened in terms of forces
  and energy. What should my work look like?
• Plenary Evaluate your test.

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A clear graph
Force (N)
CONCLUSION PAGE
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Model conclusion
If the brick is dragged along the ground, the
rough surfaces lock together and make lots of
friction. All of the surface of the brick is
touching the ground. The bigger the surface, the
more friction there is. It takes a lot of force
to drag the brick. If you use rollers, the rough
surfaces do not lock together and so there is
much less friction. So it takes much less force
to pull the block.
PREVIOUS PAGE
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Forces their effects Lesson 5

• Why is iron heavier than aluminium?

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OBJECTIVES what I am looking for

• To learn the idea of density.
• To learn to measure and compare different
  materials.

• You can measure mass in grams.
• You can measure volume in cm³ .
• You can record your results in tables.
• You can calculate the mass of 1 cm³ of each
  material.

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Equipment

• FOR GROUP USE
• Metal blocks (materials kit) Iron, brass,
  aluminium lead HAZARD
• Electronic scales
• Study guides

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Stage 1

• What is the mass of each metal block? (Measure in
  grams)
• Make a table of your results.

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Was this a fair comparison?

• Describe why your test is not fair.
• Can you work out what the mass would be if every
  block was 1 cm³?

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What is the mass of 1cm3 ?

• Can you work out what the mass would be if every
  block was 1 cm³?

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What should your results be?
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So

• Now you know which material was the most dense.

Check learning
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Plenary Any ideas?
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Finishing up

• Save any computer work.
• Equipment away please.
• Give in your books.
• Clear your table.
• WASH YOUR HANDS!

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Forces Lesson 6

• Are objects lighter under water?

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Equipment

• Objects to weigh underwater
• Forcemeters

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OBJECTIVES what I am looking for

• To learn the idea of a force called upthrust.
• To learn how to make accurate measurements of
  forces.
• To develop your ability to explain why things
  happen.
• To correctly mark forces on diagrams.

• You can draw a basic force diagram in 2D.
• You are able to measure force accurately using a
  force meter.
• You can use the computer to produce a useful
  graph that shows your results clearly.
• You can explain why forces cause things to be
  lighter in water.
• You can evaluate your test.

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What forces?
upthrust
thrust
drag
weight
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The proper way
upthrust
thrust
drag
gravity
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Instructions

• Use the study guide. Write the title date.
• Write What is the force that pulls down on the
  stone? The force that
• Draw the diagram in 2 dimensions showing the
  forces correctly.
• Use the equipment to find out if objects are
  lighter under the water. Repeat each test to get
  accurate results.
• Record your results in a table.

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Results
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Produce a spreadsheet using a computer. Use a
formula to calculate the difference column.
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Conclusion evaluation

• Explain why the objects were lighter under water.
  Make sure you show your knowledge of forces.
• Evaluate your test.

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Forces Lesson 7

• Why are some toy cars faster than others?

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Equipment

• Toy cars
• Wooden ramps
• Clinometers
• Stop watches

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OBJECTIVES

• To learn why it is important to make lots of
  measurements.
• To learn how to explain why things happen.
• To learn about friction and drag.

• To do a fair test.
• To learn why it is important to make lots of
  measurements.
• To explain why a force called friction affects
  the speed of a car.
• To explain what happens to the energy.
• To calculate speed.

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By the end of the lesson

• Be able to peruse, choose and use the right
  equipment.
• Be able to list the variables.
• Be able to write an explanation.
• Be able to measure and calculate speed.

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Force diagram
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Forces Lesson 8

• Do things float better in salty water?

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Equipment

• Hydrometers
• Salty water
• Very salty water
• Tap water
• A ball
• Transparent fish tank

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OBJECTIVES / OUTCOMES

• To learn about forces that act in different
  directions.
• To develop your ability to explain why things
  happen.

• You can peruse, choose and use the right
  equipment.
• You can measure accurately.
• You can explain why forces make this happen.
• You can evaluate your test.

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Starter

• Pushing a ball onto a bucket of water.
• Key questions
• As I push the ball down, what happens to the
  water?
• Does the water have mass? Am I lifting it?

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As the ball is pulled down by gravity, the water
is lifted.
The ball will go down until it balances the mass
of the water it is pushing out of the way.
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What if the ball was lighter?
What if the water was heavier?
How could you make the water heavier?
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Input

• BBC DVD Class Clips 1 / Materials their
  properties / Compounds mixtures / 5 Mixtures

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• Use the same hydrometer every time.
• Measure how high the hydrometer floats (in mm
  from the surface of the water to the top of the
  dowel).

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Finishing up

• Why does the hydrometer float better in very
  salty water? Write to explain why in terms of
  forces.
• Evaluate your test.

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Forces Lesson 9

• Is friction sometimes useful?

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OBJECTIVES / OUTCOMES

• To learn how friction is sometimes a useful
  force.
• To learn where friction forces happen.
• To learn how to add labels and captions.

• Your two diagrams show that you know where high
  friction is important.
• Your two diagrams show that you know where low
  friction is important.
• You can write useful captions.

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Equipment

• Video Cycling crazy

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Activities

• Video Cycling crazy
• High friction and low friction (use study guide)

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(No Transcript)
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Rounding up

• Your two diagrams show that you know where high
  friction is important.
• Your two diagrams show that you know where low
  friction is important.
• You can write useful captions.

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Forces Lesson 10

• Do pulleys help with lifting?

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Equipment

• Pulley sets
• Hang on masses
• Forcemeters
• 1kg masses
• String

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OBJECTIVES/ OUTCOMES

• To learn that pulleys are helpful for lifting.

• You can work as a team to set up the test.
• You can use a forcemeter to measure the pulling
  forces.
• You can record your results in a table.
• You can write to describe what you noticed.