Yr 10 Forces and Motion

pretest

Class notes

Class notes - Oxford text 2018-19

Some graphs

Newtons second law cloze passage

Newtons first law and inertia and cars

Revision sheet 1

Revision powerpoint

Collisions - from catalyst    https://youtu.be/6wCgmaG3Zgw

Extension worksheets for students intending to do physics next year

Key force

Miscellaneous speed and acceleration

Miscellaneous motion problems

Miscellaneous Focre rule

Miscellaneous KE and PE

Cloze word passage on friction

Acrostic on Work

Class notes-

Speed vs Velocity,,, Distance vs Displacement
1. Go for a walk and record where you went how far you wnet and how long it took to finally
Calculations and exploration
1. on a map of the school plot your travels
2.Record the number of steps
Record the time take
3 Use speed = distance / time to calculate you speed in m / s

4 a)How far from S5 did you go
b) How long did this take you?

Converting to metres per second

things to remember
1000m in 1 km
60 seconds in 1 min 60 min in 1 hr therefore there are 3600 seconds in 1 hour

to convert km / hr to m/s

step 1 change the km to m (eg km x 1000)
step 2 change hours to seconds (eg hr x 3600)
step 3 divide the answer from step 1 by the answer form step 2

OR as a short cut you can multiply m/s by 3.6 to get km/ hr

and divide km/hr by 3.6 to get m/s

USing Ticker Timers to describe motion
Make some ticker timer strips to show a constant speed - cut up a set of 3 strips of ticker paper that show 0.1s (ie 5 intervals ( 6 dots). Paste them in your book side by side. Label the vertical axis distance and the horizontal axis time.
Make a ticker timer strips to show speeding up (acceleration)
Make some ticker timer strips to show slowing down

SOme calculations

average speed = distance / time with this equation we need to watch the units -in a car our speed will be measured as km/hr, an athlete running may be measured in metres per second ie m/s

Velocity is speed in a certain direction. generaly in physics we measure in velocity in m/s. So if we have a problem in where data is provided as km/hr we will usually convert this to m/s. The reason we do this is to provide consistency when we measure other aspects of motion ( and we are following the SI units for physics)
To calculate velocity we measure the displacment (distance in a given direction) and divide by the seconds
velocity = displacement / time

When you used the ticker timers you were measuring distance and dividing by time to get the average speed for each little strip you cut up.
When you pasted each interval side by side you were making a distance tiime graph for that motion.

distance time graphs

Distance time graph

Can you describe what is happening between each of the letters?In particular what is happening from C to D.What about B to C  From A to B is a curve . A curve on a distance time graph shows acceleration.

Velocity time graph

down load the complete pdf here it shows how to calculate acceleration velocity time graph and calculating acceleration.pdf

You should know how to describe the following on a distance time graph
1. standing still
2. travelling at a constant speed
3. accelerating
4. decelerating

Acceleration

WE describe acceleration as how quickly speed changes over a certain time. So if we start with a speed of 2m/s and increase that speed to 8m/s and it has taken 2 seconds to do this we say our acceleration is 3m/s/s
the calculation for this is acceleration = change in velocity (v -u) / time where v is the final velocity and u is the initial velocity.
Worked example
a bike starts at rest ( ie initial velocity is 0 m/s) and increases its velocity for 3 seconds to a final velocity of 12 m/s. Find the accelaeration

a = (v-u)/t
a = (12 - 0) / 3 ...............ie 12 / 3
a=4m/s/s

Positive acceleration -- is speeding up. eg when you press the accelerator you in crease your speed - this is acceleration.
Negative acceleration = deceleration = slowing down eg when you put the brakes on in a car - you are decelerating.

Newtons first law

a body will stay at rest ( or stay at the same veolcity (speed with direction)) until it is acted on by a force
general formula to find force acting on a body is
Force = mass x acceleration
F = ma the answer is in N ( Newtons)

Weight and potential energy and formula
One earth we have a weight force which can be calculated by

W=mass x acceleration due to gravity

W= mg acceleration due to gravity = 9.8m/s²

e.g. W= 70 x 9.8

W= 686 newtons = 686N
If we were on the moon acceleration due to gravity is 1.6/s/s therefor our weight force would be

W=70 x 1.6

W= 112 Newton’s or 112N

Newtons Second Law

Describes how a Force is created by a mass being accelerated or F = ma
In symbols, Newton's second law can be expressed as:
 equation

The net force is the total force acting on the object. If the net force is measured in newtons (N) and the mass is measured in kilograms (kg), the acceleration can be determined in metres per second squared (m/s2).

If a large force is applied to a small mass it will accelerate very fast eg you pushing a ball
If a large force is applied to a large mass it will accelerate slowly eg you pushing an elephant

In the last example you can imagine that elephant may want to push against you. the final direction and acceleration will depend on who has the largest push or force. The overall force is called the NET force. it always has direction.

If the net force is 0 we say the opposing forces are balanced - eg you sitting on a chair.

Newtons Third Law

Newton's Third Law of Motion states that for every action there is an equal and opposite reaction. That is, when an object applies a force to a second object, the second object applies an equal and opposite force to the first object.

eLesson

Newton's Laws

Learn about Newton's laws of motion and see them being applied in everyday life.
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In fact, forces always occur in pairs. Sometimes it is painfully obvious. For example, when you catch a fast-moving softball or cricket ball with your bare hands, your hands apply a force to the ball. The ball applies an equal and opposite force to your hands — causing the pain.

Draw draw a person on a chair
how do the three laws work together

Work

8.7 Getting down to work
Work done on an object by a force is equal to the change in energy of the object.

Work is described as the amount of force required to move something a certain distance.
W = F x s where W = work and F = force and s = displacement or distance in a given direction.

Energy
The unit of energy is the Joule or J
Once something is moving we say it has Kinetic energy
and can calculate this by KE = 1/2mv x v 1/2 = half, m = mass, v = velocity

All stored energy is called potential energy. Energy can be stored in several different ways.
common calculation os of the amount of stored energy are

Potential Energy (PE) = mgh where m = mass, g = acceleration due to gravity (usually 9.8 m/s/s) and h is height off the ground in metres.
see below for worked examples
here are some other forms of stored energy.

• Elastic potential energy (also called strain energy) is present in objects when they are stretched or compressed. Stretched rubber bands and springs have elastic potential energy. So do compressed springs like the one shown below. When the hand is opened, the elastic potential energy in the compressed spring is converted into kinetic energy.
• Gravitational potential energy is present in objects that are in a position from which they could fall as a result of the force of gravity. The water in a hydro-electric dam has gravitational potential energy. When the water is released, the force of gravity pulls down on it, doing work and converting the gravitational potential energy into kinetic energy.
• Electrical potential energy is present in objects or groups of objects in which positively and negatively charged particles are separated. It is also present when like electric charges are brought close together. The most obvious evidence of electrical potential energy is in clouds during thunderstorms. When enough electrical potential energy builds up, electrons move as lightning between clouds or to the ground.
• Chemical potential energy is present in all substances as a result of the electrical forces that hold atoms together. When chemical reactions take place, the stored energy can be converted to other forms of energy or it can be transferred to other atoms. Chemical potential energy is a form of electrical potential energy.
• Nuclear energy is the potential energy stored within the nucleus of all atoms. In radioactive substances, nuclear energy is naturally converted to other forms of energy. In nuclear reactions, such as those in nuclear power stations, in nuclear weapons and on the sun and other stars, nuclei are split or combine together. As a result, some of the energy stored in the reacting nuclei is converted into other forms of energy.

Energy efficiency

Efficiency = (the useful output / energy input) *100

eg Aball is dropped from 100cm it bounces up 40 cm.

The efficiency of the ball is mgh2/ mgh2

REview of formulae

Weight and potential energy and formula
One earth we have a weight force which can be calculated by

W=mass x acceleration due to gravity

W= mg acceleration due to gravity = 9.8m/s²

e.g. W= 70 x 9.8

W= 686 newtons = 686N
If we were on the moon acceleration due to gravity is 1.6/s/s therefor our weight force would be

W=70 x 1.6

W= 112 Newton’s or 112N
Energy and force
energy is neither created nor destroyed but it is transformed/

e.g. solar energy is transformed into electrical energy is transformed into moving energy
(a toy solar powered car or fan)

moving energy is called kinetic energy

kinetic energy = 1/2mv²
Find the KE of a car mass 1000kg moving at 10m/s
KE=1/2 x 1000 x 10
KE= 50000 joules or 50KJ

Gravitational potential energy (GPE)
GPE= mass x acceleration due to gravity x height (m)
E.g. find the GPE of a car of mass 1000 suspended 10m above the ground (g=9.8m/s/s)
GPE = 1000 x 9.8 x 10

GPE= 98000 joules or 98KJ

Key points
Newtons laws
first law - object stays at rest until acted on by a force
second law when a force acts on an object it will accelerate at a rate in proportion to the size of the force and the size of the mass it acts on F = ma
third law - For every force there is an equal and opposite reaction collisions forces exert equal and opposite. examples are collisions and inertia

Graphs Dist vs time graph ie dist / time
Distance / time = speed
a special case is a displacement time graph i.e. velocity = displacement / time
Big deal is displacment is distance with direction. This means displacement could be smaller than distance over the same journey eg if you went to the shops and got half way before you realised you forgot your purse and went back home and then went to the shops again. Displacement only looks at how far are you from your start ( home) While distance takes into account the return trip and back to the sshop
Velocity is speed in a given direction = this means overall velocity has to take into account the velocity back toward the starting point
speed vs time = tells us the acceleration

calculations ;
Hint how to do a physics problem
1 read the question and underline the data
2. draw a picture of what is happening
3. list the data required and the formula you might use - and convert to correct units
4. plug the data into the formula

acceleration = (final velocity – initial velocity) /times

a= (v-u)/t or v= u + at

example; find the final velocity of a giraffe with a mass of 500kg that starts form 2m/s and accelerates at 5m/s/s for 10 seconds
[from the question we want to find v we know u = 2 , a = 5 and t = 10]

v = 2+5 x 10

v= 52m/s

Part 2 what force is require to accelerate the giraffe to this velocity?

f= m x a

f= 500 x 5

f= 2500N
What is the kinetic energy of the giraffe

KE=1/2 x m x v x v

KE= ½ x 500 x 52 x 52

KE= 676000J or 676KJ
_

Forces and Motion – key concepts Name: _

 Key Concept Vocabulary – Words To Learn 1. Relationships between force, mass and movement. 2. Energy changes are responsible for changes observed in motion and shape. Distance and Displacement Speed and Velocity Acceleration and deceleration Scalar and Vector quantities Average and instantaneous Standard International Units Force Friction Air resistance Lift thrust Weight Electrostatic Magnetic Inertia Mass Equilibrium/balance Action/reaction Gravity Weightlessness Terminal velocity Kinetic Energy Potential (stored) energy: Gravitational & Elastic

Class Notes 2015

NOTES 2013

Forces acting on us
 Person ........Forces acting on the person Parachutist Gravity, air resistance, wind Bungee jumper gravityElastic force Skier gravity frictionforce exerted by the earth Cyclist gravity, friction, pushing the pedals Reader InLine Skater friction, pushing their feet, air resistance, Swimmer bouyancy of the water, gravity, themselves pulling through the water
Non contact forces include - electrostatic forces, magnetic forces, gravity

Average speed can be measured in many units eg km/hr or m/s or cm/minute
In science we usually convert to metres per second

Do the online section of the test. click on the link
http://www.classroomclipboard.com/490625/Home/Test/34f5c4e538c7027703b0f361c77c62d8#/InitializeTest.xaml
Type your class as part of your last name eg ebony 10DDunkley
the test access code is X86S5
the written section will be done in class

Forces and Motion – key concepts Name: _
 Key Concept Vocabulary Relationships between force, mass and movement. Energy changes are responsible for changes observed in motion and shape. Distance and Displacement Speed and Velocity Acceleration and deceleration Scalar and Vector quantities Average and instantaneous Standard International Units Force Friction Air resistance Lift thrust Weight Electrostatic Magnetic Inertia Mass Equilibrium/balance Action/reaction Gravity Weightlessness Terminal velocity Kinetic Energy Potential (stored) energy: Gravitational & Elastic

 Priority Suggested Activities Extension & Variation 6.1 page 217 -9 Formulae for speed/velocity Conversion of units Average and instantaneous Understanding data from graphs Read 6.1 and answer Questions: 1-4 and 8-15 page 221 Activity: They’ve got the runs page 225 Prac: Chain reaction and Driving reaction times The Reflex tester Homework 6.1 Interactive: Describing Movement http://www.media.pearson.com.au/schools/cw/au_sch_rickard_sd4_1/dnd/sci4_5_1.html Interactive: Understanding graphs http://www.media.pearson.com.au/schools/cw/au_sch_rickard_sd4_1/int/GraphMovement.html 6.2 page 229-230 Acceleration – speeding up or slowing down Rate of change (of speed/velocity) Speeding up/slowing down due to gravity Read 6.2 Questions: 1 – 6 page 230 Activity: an accelerometer page 232 Questions 7 – 8 and 11 – 12 page 231 Extension - watch how they measure speed and acceleration on these graphs http://physics.info/motion-graphs/ 6.3 page 234 - 236 Forces Experiencing Forces Newton’s Law of inertia Read 6.3 and answer Questions: 1 – 8 page 236 Prac: Experiencing Forces Booklet: forcescollisions.doc 1.Types of Forces pages 3 - 4 2. Newton’s Ping Pong Balls pages 6-7 3. Circular Motion Page 8 Prac: Crash test dummies page 238 and Inertial eggs page 239 Homework 6.3 Using Data sensors to measure motion a prac: Detecting Motion using digital sensors.docx Questions 9 – 19 page 237 Assignment: Homework 6.5 as a research crash test dummies http://archive.org/details/crashdummies1 http://www.youtube.com/watch?v=d7iYZPp2zYY can you measure the velocity of various parts of the body? http://www.youtube.com/watch?v=OoJqCsHAak8&feature=related 6.4 page 240 -241Newton’s 2nd Law, the relationship between force and mass. Net Force Drawing forces on the page – vectors Questions: 1- 6 page 241 Prac: page 244 Newtons laws videos Roller coasters exercise http://www.nbclearn.com/portal/site/learn/science-of-the-summer-olympics Video 1 Strength and flexibility of Oscar Pistorius Q. Describe how the prosthetic legs help him run. What forces are involved? Video 2 Biomechanics of Usain Bolt Q. In order to achieve top acceleration and maintain speed Bolt needs to use more force to move more mass ( he is very tall for a sprinter) how does he do this? Video 3 The impact of Jenny simpson Q. How does antigravity treadmill work? How is it related to the formula F = ma Video 4 Maximising the long jump of Brian Clay Q. How does gravity affect Bryan's velocity? How does his take off angle help achieve a long jump. Video 5 Sarah Robies and the mechanics of weightlifting Q. How does sarah achieve such explosive power in weightlifting. Now go to http://www.nbclearn.com/portal/site/learn/science-of-the-olympic-winter-games Choose 3 videos that could be used to explain Newtons 3 laws. List the videos and write in bullet points why and how the video could be used to explain the each law. Questions 7-10page 241 6.5 page 245-246 Newton’s 3rd Law Action/reaction forces Prac: Balloon Rockets 1 and 2 page 248 Questions: 1-5 page 246 Video: Collisions Questions 6-11 page 247 interactive : Newton’s Laws http://www.media.pearson.com.au/schools/cw/au_sch_rickard_sd4_1/dnd/sf4_0502.html Interactive: Resultant Force http://www.media.pearson.com.au/schools/cw/au_sch_rickard_sd4_1/int/forces.html Collision Game: http://www.students.uni-mainz.de/rathb000/Pinball/Game.html 6.6 page 249-251 Gravity Weight Air resistance Weightlessness Questions: 1-12 page 251 Prac: Observing weightlessness page 255 Homework 6.6 Question 13 -18 page 251 Moon Video click on “motion due to Gravity” link of http://www.vicphysics.org/index.php?id=263 6.7page 256-258 energy, Work, Kinetic energy Potential or stored energies: Gravitational potential energy Elastic potential energy Questions: 1-7page 258 Prac: Extension of an elastic band and Efficiency of a roller coaster(hint: tape tubing to the cupboard/wall) page 260-261 Revision Chapter Review page 262 Homework 6.9 Interactive crossword: http://wps.pearsoned.com.au/sd4/50/12994/3326638.cw/index.html Test plus 1 A4 sheet of summary notes

Motion: Investigating Distance, Displacement, Speed and Velocity
Investigating Distance, Displacement, Speed & Velocity.docx
Your task, in a group of 3 or 4, is to map out a course around the school. Individuals in your group will be timed whilst travelling this course. From this activity, you will be required to work out values of distance, displacement, speed and velocity.

Materials (per group):

- Trundle wheel
- Stopwatch
- Pen
- School map (see over the page)

Method:
1. Using the trundle wheel, measure a course around the school and record it on your map. Use the guidelines below:

- Your course must be between 100 and 200 metres

- You must stay within school grounds

- Your course cannot include going into classrooms

- In order to be able to calculate displacement you must be able to measure, in a straight line, from the starting position to the final position of your course, as shown on the right. If this line is through a building or other object, you will not be able to measure displacement.

1. Record the distance of your course in the table below. Remember to include the units.

1. Measure from the end point of your course to the starting point of your course in a straight line in order to find the displacement. Record this in the table below.

1. Choose one person from the group to travel your course. They must do so 2 times, each using a different form of locomotion. Choose 2 of the following examples: walking, jogging, skipping, lunges, hopping. Each time the person travels the course, you should record their time with the stopwatch and write it in the table below.

Results:

 Mode of Locomotion Distance of Course Displacement of Individual Time Taken Average Speed Average Velocity

Discussion:
1. Describe the distance between distance and displacement.
2. Calculate the average speed for each mode of locomotion using the formula distance travelled/time taken.
3. Calculate the average velocity for each mode of locomotion using the formula displacement/time.
4. Describe the difference between instantaneous speed and average speed.
5. Describe the difference between speed and velocity.

Map of the school
 C:Program FilesMicrosoft OfficeMEDIACAGCAT10j0304933.wmf

Weight and potential energy and formula
One earth we have a weight force which can be calculated by

W=mass x acceleration due to gravity

W= mg acceleration due to gravity = 9.8m/s²

e.g. W= 70 x 9.8

W= 686 newtons = 686N
If we were on the moon acceleration due to gravity is 1.6/s/s therefor our weight force would be

W=70 x 1.6

W= 112 Newton’s or 112N
Energy and force
energy is neither created nor destroyed but it is transformed/

e.g. solar energy is transformed into electrical energy is transformed into moving energy
(a toy solar powered car or fan)

moving energy is called kinetic energy

kinetic energy = 1/2mv²
Find the KE of a car mass 1000kg moving at 10m/s
KE=1/2 x 1000 x 10
KE= 50000 joules or 50KJ

Gravitational potential energy (GPE)
GPE= mass x acceleration due to gravity x height (m)
E.g. find the GPE of a car of mass 1000 suspended 10m above the ground (g=9.8m/s/s)
GPE = 1000 x 9.8 x 10

GPE= 98000 joules or 98KJ

Key points
Newtons laws
first law - object stays at rest until acted on by a force
second law when a force acts on an object it will accelerate at a rate in proportion to the size of the force and the size of the mass it acts on F = ma
third law - For every force there is an equal and opposite reaction collisions forces exert equal and opposite. examples are collisions and inertia

Graphs Dist vs time graph ie dist / time
Distance / time = speed
a special case is a displacement time graph i.e. velocity = displacement / time
Big deal is displacment is distance with direction. This means displacement could be smaller than distance over the same journey eg if you went to the shops and got half way before you realised you forgot your purse and went back home and then went to the shops again. Displacement only looks at how far are you from your start ( home) While distance takes into account the return trip and back to the sshop
Velocity is speed in a given direction = this means overall velocity has to take into account the velocity back toward the starting point
speed vs time = tells us the acceleration

calculations ;
Hint how to do a physics problem
1 read the question and underline the data
2. draw a picture of what is happening
3. list the data required and the formula you might use
4. plug the data into the formula

acceleration = (final velocity – initial velocity) /times

a= (v-u)/t or v= u + at

example; find the final velocity of a giraffe with a mass of 500kg that starts form 2m/s and accelerates at 5m/s/s for 10 seconds
[from the question we want to find v we know u = 2 , a = 5 and t = 10]

v = 2+5 x 10

v= 52m/s

Part 2 what force is require to accelerate the giraffe to this velocity?

f= m x a

f= 500 x 5

f= 2500N
What is the kinetic energy of the giraffe

KE=1/2 x m x v x v

KE= ½ x 500 x 52 x 52

KE= 676000J or 676KJ