LESSON 1

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LESSON 1. A TIP FROM THE TOP. Examiner Edward says: The key to success is being able to use the equations accurately and then write the correct units. Introducing……. The DATA SHEET You get this sheet with the exam

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Presentation Transcript

A TIP FROM THE TOP

Examiner Edward says:

The key to success is being able to use the equations accurately and then write the correct units

Introducing……

The DATA SHEET

You get this sheet with the exam

Contains all of the equations that you will need to choose during the exam

THEREFORE USE IT!!!

Using the equationsTo get a Grade C

A car has a mass of 10,000 kg. What is the weight of the car on Earth?

(use gravitational field strength = 10N/kg)

STEP 1: Choose the correct equation from the data sheet

(use gravitational field strength = 10N/kg)

Weight = Mass X Gravity

= 10000 X 10

= 100000

What’s missing?

IT

I WONDER WHAT FORCES ARE MEASURED IN?

(use gravitational field strength = 10N/kg)

Weight = Mass X Gravity

= 10000 X 10

= 100000N

Lesson objectivesHave we hit any yet?

ALL: Will BE ABLE to name the forces that act on objects and be able to draw them in the right direction on a force diagram (grade D)

MOST: Will UNDERSTAND how to use simple equations to work out calculations (grade C)

SOME: Will BE ABLE to rearrange the formula to get the correct equation and then apply to gain the correct answer with the correct units (grade B)

A TIP FROM THE TOP

Examiner Edward says:

You will need to be able to rearrange the formula and use it

Weight = Mass X Gravity

Transfer the equation above into the triangle

Weight

Gravity

Mass

ERIC EARTH’S TIP OF THE DAY

Use the cover up rule to work out the equation for MASS!!!

Weight

Gravity

Mass

PLACE IT OVER MASS

Weight

Gravity

Mass

WHAT’S LEFT?

Weight

Gravity

Mass

A man has a mass of 150kg and a weight of 240N when on the Moon. Write out the equation to work out the gravitational field strength and then use it to calculate the answer. Show all of your working

Gravity = Weight ÷ Mass

= 240 ÷ 150

= 1.6 N/kg

Lesson objectivesHave we hit any yet?

ALL: Will BE ABLE to name the forces that act on objects and be able to draw them in the right direction on a force diagram (grade D)

MOST: Will UNDERSTAND how to use simple equations to work out calculations (grade C)

SOME: Will BE ABLE to rearrange the formula to get the correct equation and then apply to gain the correct answer with the correct units (grade B)

What is the mass of an elephant that has a kinetic energy of 25000J and moves with a velocity of 5 m/s?

First one to spot the correct equation gets 25 Vivos

Don’t PANIC!!!!!

BOB THE BUILDER

“We can FIX IT……but you’ll need to watch carefully”

STEP 1

• Write down the original kinetic energy equation
• K.E = ½ x MASS X VELOCITY2

What is the mass of an elephant that has a kinetic energy of 25000J and moves with a velocity of

5 m/s?

STEP 2

• The question wants you to work out the mass, so you must take everything else over to the other side
• K.E = ½ x MASS X VELOCITY2

What is the mass of an elephant that has a kinetic energy of 25000J and moves with a velocity of

5 m/s?

STEP 3

• Whatever the factors did on one side, they must do the opposite on the other. So ½ and velocity are multiplied by mass on one side so must be divided on the other side
• K.E ÷ ( ½ x VELOCITY2) = MASS

What is the mass of an elephant that has a kinetic energy of 25000J and moves with a velocity of

5 m/s?

STEP 4

• Now use your rearranged equation to work out the question
• K.E ÷ ( ½ x VELOCITY2) = MASS
• 25000 ÷ ( ½ x 52) = MASS

What is the mass of an elephant that has a kinetic energy of 25000J and moves with a velocity of

5 m/s?

What is the mass of an elephant that has a kinetic energy of 25000J and moves with a velocity of 5 m/s?

MASS = 2000 kg

A TIP FROM THE TOP

(I’M BACK)

Examiner Edward says:

The key to success is being to use the equations accurately and then write the correct units

Usain is built like a unit and he just loves units!!!! And he wants you to feel the love too!Therefore every time we meet a new factor, write down the units at the back of your book!

USAIN’S

UNITS

Lesson objectivesHave we hit any yet?

ALL: Will BE ABLE to name the forces that act on objects and be able to draw them in the right direction on a force diagram (grade D)

MOST: Will UNDERSTAND how to use simple equations to work out calculations (grade C)

SOME: Will BE ABLE to rearrange the formula to get the correct equation and then apply to gain the correct answer with the correct units (grade B)

Look at the objects below and write down any force that you can think of that is acting on them

“Be FORCEFUL!!”

How many did you get?
• gravity
• friction
• air resistance
• water resistance
• upthrust
• thrust

Air resistance and water resistance are collectively known as DRAG

Lesson objectivesHave we hit any yet?

ALL: Will BE ABLE to name the forces that act on objects and be able to draw them in the right direction on a force diagram (grade D)

MOST: Will UNDERSTAND how to use simple equations to work out calculations (grade C)

SOME: Will BE ABLE to rearrange the formula to get the correct equation and then apply to gain the correct answer with the correct units (grade B)

FORCE

DIAGRAMS

“The sum of the forward forces acting on an object subtract the backward forces”

WORDS

RESULTANT

FORCES

Lesson objectivesHave we hit any yet?

ALL: Will UNDERSTAND the definition of a resultant force and will BE ABLE to work out the resultant forces in given situations (grade C)

MOST: Will UNDERSTAND how different resultant forces affect the movement of an object (grade B)

SOME: Will BE ABLE to explain what happens to an object with reference to the resultant force (grade A)

Scenario 1

Friction 8N

Thrust 10N

Drag 2N

So resultant force = ON.

Car will stay moving at a constant speed

Scenario 2

Friction 6N

Thrust 10N

Drag 2N

So resultant force = 2N forwards.

Car will accelerate

Scenario 3

Friction 11N

Thrust 10N

Drag 4N

So resultant force = 5N backwards. Car will decelerate

If the forward forces are equal to the backward forces, then they are _____________ and the resultant force = _____N. In this case, the object will continue doing as it was - this could be staying still or to continue moving at a ___________ speed.

If forces are ________, then the object changes speed and this is affected by the _____________ force. If there is more force ________, the resultant force will be ___________ and the object accelerates. If there is more force backwards, the resultant force is ___________ and then the object will________________.

If the forward forces are equal to the backward forces, then they are balanced and the resultant force = 0N. In this case, the object will continue doing as it was - this could be staying still or to continue moving at a constantspeed.

If forces are unbalanced, then the object changes speed and this is affected by the resultant force. If there is more force forwards, the resultant force will be positive and the object accelerates. If there is more force backwards, the resultant force is negative and then the object willdecelerate.

Lesson objectivesHave we hit any yet?

ALL: Will UNDERSTAND the definition of a resultant force and will BE ABLE to work out the resultant forces in given situations (grade C)

MOST: Will UNDERSTAND how different resultant forces affect the movement of an object (grade B)

SOME: Will BE ABLE to explain what happens to an object with reference to the resultant force (grade A)

To try
• A stone is dropped into a pond. The weight of the stone is 8N. The water resistance is 8N. What happens to the speed of the stone? Explain your answer
• A car is travelling at 15m/s. It has a thrust of 100N. The friction is 75N. What happens to the speed of the car? Explain your answer
• A plane is travelling through the air at 200m/s. If the plane slows down when there is an air resistance of 10000N, what must be the size of the thrust force?
Lesson objectivesHave we hit any yet?

ALL: Will UNDERSTAND the definition of a resultant force and will BE ABLE to work out the resultant forces in given situations (grade C)

MOST: Will UNDERSTAND how different resultant forces affect the movement of an object (grade B)

SOME: Will BE ABLE to explain what happens to an object with reference to the resultant force (grade A)

Assessment

Greg and the car have a mass of 500kg

Work out the acceleration of the lorry shown above

Thrust 5000N

Friction and drag 1500N

If I was a gambler, I would bet there were two different answers found by the pupil’s in this class!

10 m/s2

7 m/s2

But which is correct?

Why?

Greg and the car have a mass of 500kg

The force used in the equation has to be the resultant force!

So 5000 – 1500 = 3500N

Thrust 5000N

Friction and drag 1500N

Olympic CHAMPION

Usain gets out of the blocks when the gun goes – what must he do then?

A plane went from being stationary at the start of the runway to moving at 300 m/s in 20 seconds. What was the acceleration?

Acceleration = Change in velocity ÷ Time taken

= 300 ÷ 20

= 15 m/s2

A bus is travelling along at 20 m/s. It then accelerates for 10 seconds and reaches the velocity of 80 m/s. What is the acceleration?

THE ACCELERATION OLYMPICS

Look at the animals and their race details below. Work out the order of these animals, from the lowest to the highest, by calculating their accelerations

From 0m/s to 5m/s in 10 seconds

From 10m/s to 25m/s in 3 seconds

From 2m/s to 10m/s in 4 seconds

From 5m/s to 25m/s in 2 seconds

From 0m/s to 9m/s in 3 seconds

IN 5th PLACE

5 ÷ 10 = 0.5m/s2

IN 4th PLACE

8 ÷ 4 = 2m/s2

IN 3rd PLACE

9 ÷ 3 = 3m/s2

IN 2nd PLACE

15 ÷ 3 = 5m/s2

THE WINNER

20 ÷ 2 = 10m/s2

So that’s how to work out the acceleration!

Acceleration = Change in velocity ÷ time taken

Transfer the equation above into the triangle

Change

Time

Acceleration

EINSTEIN’S TIP OF THE DAY

Use the cover up rule to work out the equation for change in velocity!!!

Change

Time

Acceleration

PLACE IT OVER CHANGE

Change

Time

Acceleration

WHAT’S LEFT?

Change

Time

Acceleration

NOW YOU TRY

Use the cover up rule to work out the equation for Time taken

Lesson objectivesHave we hit any yet?

ALL: Will UNDERSTAND the definition of a resultant force and will BE ABLE to work out the resultant forces in given situations (grade C)

MOST: Will UNDERSTAND how different resultant forces affect the movement of an object (grade B)

SOME: Will BE ABLE to explain what happens to an object with reference to the resultant force (grade A)

A car accelerates at 6 m/s2 when a resultant force of +1500N acts on it. What is the mass of the car?

SELF ASSESS

A car accelerates at 6 m/s2 when a resultant force of +1500N acts on it. What is the mass of the car?

Mass = Force ÷ Acceleration

= 1500 ÷ 6

= 250kg

• Give yourself 1 mark for each of the following:
• The equation
• The working
• The correct units

PEER ASSESS

Give them one mark for each of the ticks they achieved:

• Drawn as a line graph
• Time on the x axis and Velocity on the y axis
• Both axes labelled with a title AND units
• Even scale used on both axes
• All points plotted accurately
• Straight lines drawn between the points
Velocity-Time Graph

Where is acceleration on this graph?

Velocity

(m/s)

Time

(seconds)

Velocity-Time Graph

But which one is the greater acceleration?

Velocity

(m/s)

Time

(seconds)

The bigger the acceleration, the steeper the line on the graph

SELF ASSESS

• Give yourself 1 mark for each of the following:
• The working
• The correct units

30 ÷ 10 = 3 m/s2

30 ÷ 15 = 2 m/s2

Velocity

(m/s)

-60 ÷ 5 = -12 m/s2

Time

(seconds)

Lesson objectivesHave we hit any yet?

ALL: Will BE ABLE to use a velocity-time graph to recognise when an object is accelerating, decelerating or moving at a constant velocity (grade C)

MOST: Will BE ABLE to use a velocity-time graph to work out the acceleration (grade B)

SOME: Will BE ABLE to explain how the resultant forces acting on an object affects its motion and how this will be shown on the velocity-time graph (grade A)

Velocity-Time Graph

Constant velocity

Velocity

(m/s)

Time

(seconds)

Velocity-Time Graph

And

here?

Deceleration

Velocity

(m/s)

Time

(seconds)

Lesson objectivesHave we hit any yet?

ALL: Will BE ABLE to use a velocity-time graph to recognise when an object is accelerating, decelerating or moving at a constant velocity (grade C)

MOST: Will BE ABLE to use a velocity-time graph to work out the acceleration (grade B)

SOME: Will BE ABLE to explain how the resultant forces acting on an object affects its motion and how this will be shown on the velocity-time graph (grade A)

A velocity time graph can be used to show the different motions of an object. An object is _______________ when there is a line which looks like _____. The steeper the line, the ___________ the acceleration. In this case, the resultant force acting on the object must be ____________ as there are more ____________ forces than backward forces.

A horizontal line on the graph means that the object is moving at a _____________ velocity. In this case the resultant force must be _____ as the forward forces __________ the backward forces.

Deceleration is shown on a graph with a line that looks like _____. When a car decelerates, the forward forces are _______ than the backward forces and therefore the __________ force is ___________.

A velocity time graph can be used to show the different motions of an object. An object is accelerating when there is a line which looks like . The steeper the line, the greater the acceleration. In this case, the resultant force acting on the object must be positive as there are more forward forces than backward forces.

A horizontal line on the graph means that the object is moving at a constant velocity. In this case the resultant force must be zero as the forward forces equal the backward forces.

Deceleration is shown on a graph with a line that looks like . When a car decelerates, the forward forces are less than the backward forces and therefore the resultant force is negative.

Lesson objectivesHave we hit any yet?

ALL: Will BE ABLE to use a velocity-time graph to recognise when an object is accelerating, decelerating or moving at a constant velocity (grade C)

MOST: Will BE ABLE to use a velocity-time graph to work out the acceleration (grade B)

SOME: Will BE ABLE to explain how the resultant forces acting on an object affects its motion and how this will be shown on the velocity-time graph (grade A)

JUST CHECKING

Look at the table below and work out which of the rows is correct

FINGERS CROSSED FOR FLOPSY

Flopsy has escaped from her hutch and is now loose on the road. She has found herself onto the busy A road near the house and has run out in front of Greg in his car!!!

Greg has just noticed her and being the rabbit lover that he is, he really hopes he stops in time!

STOPPING DISTANCE

What two things have to happen before he stops?

“The distance that an object travels from the point the stimulus is seen until the point when the object comes to a halt”

WORDS

STOPPING DISTANCE

BRAKING DISTANCE

THINKING DISTANCE

“The distance that an object travels from the point the brake is applied until the point when the object comes to a halt”

“The distance that an object travels from the point the stimulus is seen until the point when the brake is applied”

Lesson objectivesHave we hit any yet?

ALL: Will KNOW that the stopping distance consists of the thinking distance added to the braking distance (grade C)

MOST: Will BE ABLE to name the factors that would increase the thinking or braking distance (grade B)

SOME: Will UNDERSTAND what happens to energy forms during the process of braking (grade A)

Flopsy wishes he stayed in the hutch!

What happens to the kinetic energy?

What happens to this energy?

If the police officer touches the ground where the skids of the car are, what should he notice?

What is the deceleration if the change in velocity took 2.5 seconds?

The ups and downs of BRAKING!

Stopped at 0m/s

Moving at 30m/s

• What happens to the kinetic energy? DECREASES
• What happens to this energy? IT IS CONVERTED INTO HEAT ENERGY
• If the police officer touches the ground where the skids of the car are, what should he notice? HOT ON THE GROUND
• What is the deceleration if the change in velocity took 2.5 seconds? 30 ÷ 2.5 = 12 m/s2

The ups and downs of BRAKING!

Stopped at 0m/s

Moving at 30m/s

BRAKING

When the brakes of a vehicle are applied, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases

Lesson objectivesHave we hit any yet?

ALL: Will KNOW that the stopping distance consists of the thinking distance added to the braking distance (grade C)

MOST: Will BE ABLE to name the factors that would increase the thinking or braking distance (grade B)

SOME: Will UNDERSTAND what happens to energy forms during the process of braking (grade A)

Think back to the lessons on forces and write down all the forces acting on me – don’t forget to add arrows

Gravity (or weight)

• Friction
• Air resistance
• Water resistance
• Upthrust
• Thrust
Say what YOU see!(2 words)

Big weight _________

Bristol

________

Football

Club

WORDS

TERMINALVELOCITY

Lesson objectivesHave we hit any yet?

ALL: Will KNOW the forces that act on objects as they fall through air (grade D)

MOST: Will UNDERSTAND the term terminal velocity and be able to explain how an object gets into this state (grade C)

SOME: Will BE ABLE to explain the shape of a velocity-time graph as an object falls through the air in terms of forces and velocity (grade A)

Number 1

From the moment, I jump out of the plane, I feel like I am getting faster and faster

Number 2

Once I have dropped what seems like miles, I feel like I am going at top velocity – not getting faster nor slower

Number 3

When I pull my parachute, it feels like I shoot upwards – but I don’t, I’m just slowing down

Number 4

This is my favourite part – just floating at the same velocity towards the ground taking in all the sights

Number 5

Eventually, I hit the floor and I’m just happy I’m ALIVE!

Sketch graphs

A sketch graph is one where you do not plot points, but instead make a rough drawing of what the shape of the graph will be by looking at the results or predict what it will look like using your knowledge

Although you don’t plot exact points on a sketch graph, you still must label the axes!

EXTEND

Label the lines on your graph explaining the sizes of the forces acting on the skydiver

1 mark for each:

• Line
• Explanation
How did you do?

Terminal velocity

Weight is now equal to the air resistance

Accelerating

Weight is greater than the air resistance

Decelerating

Weight is now less than the air resistance

Terminal velocity

Weight is equal to the air resistance

Velocity

(m/s)

Stopped

Both weight and air resistance are 0

Time

(seconds)

Lesson objectivesHave we hit any yet?

ALL: Will KNOW the forces that act on objects as they fall through air (grade D)

MOST: Will UNDERSTAND the term terminal velocity and be able to explain how an object gets into this state (grade C)

SOME: Will BE ABLE to explain the shape of a velocity-time graph as an object falls through the air in terms of forces and velocity (grade A)

JUST CHECKING

What would the resultant forces be at the different points?

(positive, negative or zero)

ZERO

POSITIVE

NEGATIVE

Velocity

(m/s)

ZERO

ZERO

Time

(seconds)

Lesson objectivesHave we hit any yet?

ALL: Will KNOW the forces that act on objects as they fall through air (grade D)

MOST: Will UNDERSTAND the term terminal velocity and be able to explain how an object gets into this state (grade C)

SOME: Will BE ABLE to explain the shape of a velocity-time graph as an object falls through the air in terms of forces and velocity (grade A)

Ellie presents herself to her doctor really worried about a printout she has just got out of a weighing machine. She knows that she hasn’t been keeping to her diet recently but she cant understand why the figure she has circled is so high.

Can you help the doctor figure it out?

WILL’S WEIGHING MACHINE

Age: 52

Height: 5ft4in

Mass: 55kg

Weight: 550N

### Doctor’s Orders

“The weight of an object depends on gravity and because gravity is different on different planets, the weight will change.Weight is measured in Newtons”

WORDS

WEIGHT

“The mass of an object is the amount of matter it contains and is always the same, no matter the planet.Mass is measured in kilograms”

WORDS

MASS

Lesson objectivesHave we hit any yet?

ALL: Will KNOW the differences between mass and weight and their units (grade C)

MOST: Will KNOW the equation to work out an object’s weight and will BE ABLE to apply to calculations (grade B)

SOME: Will BE ABLE to calculate the mass and gravitational field strength using the rearranged weight equation (grade A)

Measured in N

Weight

Measured in kg

Gravity

Measured in N/kg

Mass

(use gravitational field strength = 10N/kg)

Weight = Mass X Gravity

= 10000 X 10

= 100000N

An astronaut and his equipment have a mass of 150kg. What is the weight when he is standing on the Moon?

(use gravitational field strength = 1.6N/kg)

Lesson objectivesHave we hit any yet?

ALL: Will KNOW the differences between mass and weight and their units (grade C)

MOST: Will KNOW the equation to work out an object’s weight and will BE ABLE to apply to calculations (grade B)

SOME: Will BE ABLE to calculate the mass and gravitational field strength using the rearranged weight equation (grade A)

Begin by standing on the Newton scales to find your weight on Earth. Then use your knowledge and the information below to complete the rest of the calculations.

On the Earth, gravity is 10N/kg

• On Earth, my mass is ___ kg
• On Earth, my weight is ____ N

I then fly to the moon (gravity = 1.6N/kg)

• On the moon, my mass is ___ kg
• On the moon, my weight is ____ N

John puts himself on the scales and finds out that he has a mass of 65kg. If he were to fly to the moon, what would the scales read (gravity on moon is 1.6N/kg)?

A: 65N

B: 65kg

C: 104N

D: 104kg

1

A: 65kg

B: 65N

C: 650kg

D: 650N

2

A: 65kg

B: 65N

C: 6.5N

D: 104N

3

If John’s wife knew her weight was 420N on Earth, what would her mass be?

A: 42kg

B: 42N

C: 420kg

D: 4200kg

4

Which of the following statements is correct?

A: The mass and weight of an object stay the same wherever it is in the Universe

B: The mass of an object is dependent on gravity but the weight is always the same

C: The mass of an object is always the same but the weight is dependent on gravity

D: The mass of an object is always equal to the weight of the object

5

Lesson objectivesHave we hit any yet?

ALL: Will KNOW the differences between mass and weight and their units (grade C)

MOST: Will KNOW the equation to work out an object’s weight and will BE ABLE to apply to calculations (grade B)

SOME: Will BE ABLE to calculate the mass and gravitational field strength using the rearranged weight equation (grade A)

Tom needs your help!!!!He doesn’t understandwhy every time he dives into the pool, his fingers, the top of his head and his shoulders feel really warm.He has even asked for the pool to be made colder, but it doesn’t make any difference.Can Science explain it?

TOM’S TEASER

FRICTION

And

FLUIDS

The faster an object moves through a fluid (liquid or gas), the greater the frictional force that acts on it – and therefore the greater the heat energy that is given out

Compare the forward force on the bike with the backward force on the bike when Victoria Pendleton was travelling at a constant speed.

Victoria then crouched down over the handlebars to make herself more streamlined, as shown below.She continued to pedal with the same force as before.Compare the forward and backward forces acting on her now

The lift in a tall building hangs from a strong cable. The movement of the lift is affected by only two forces.These forces are the tension in the cable and the weight of the lift.

The lift is not moving.

How do the sizes of the two forces compare?

The tension is greater than the weight

The tension is equal to the weight

The tension is less than the weight

The lift in a tall building hangs from a strong cable. The movement of the lift is affected by only two forces.These forces are the tension in the cable and the weight of the lift.

• When the lift is moving upwards and getting faster, how do the forces compare?
• The tension is greater than the weight
• The tension is equal to the weight
• The tension is less than the weight

The lift in a tall building hangs from a strong cable. The movement of the lift is affected by only two forces.These forces are the tension in the cable and the weight of the lift.

• When the lift is moving upwards at a steady speed, how the forces compare?
• The tension is greater than the weight
• The tension is equal to the weight
• The tension is less than the weight

The lift in a tall building hangs from a strong cable. The movement of the lift is affected by only two forces.These forces are the tension in the cable and the weight of the lift.

• When the lift is moving upwards and gets near to the top, it starts to slow down. How do the size of the forces compare?
• The tension is greater than the weight
• The tension is equal to the weight
• The tension is less than the weight
A man finds out that he has a mass of 65 kg on Earth. Which of the following is correct?

A: The man’s weight on Earth is 65N

B: The man’s mass on The Moon is 65kg

C: The man’s weight on The Moon is 65N

D: The man’s weight on Earth is 6.5N

Grandpa Joe is a very lucky man. He has just won a trip to the Moon. However, he is not so clever,

He knows that his mass is 60kg on Earth and now he wants to know the answers to these questions!!

• How much did Grandpa Joe weigh on Earth? (tip gravity = 10N/kg)
• How much did Grandpa Joe weigh on the Moon? (tip gravity = 1.6N/kg)
• What was Grandpa Joe’s mass on the Moon?

SELF-ASSESS

MASS = 60Kg

WEIGHT = 600N

MASS = 60Kg

WEIGHT = 96N