Student Notes Y10

FORCE AND MOTION
1. Define a force as a push or a pull.
2. Describe the motion of an object using terms such as speeding up, slowing down, constant speed and
stationary. Acceleration and deceleration.
3. Draw labelled diagrams showing all the forces acting on an object in motion (constant speed or
accelerated) or an object at rest. Forces labelled as either thrust, friction, gravity and support.
4. Recognise that unbalanced forces will cause acceleration or deceleration (and change of direction or
shape)
5. Recognise that constant speed is the result of balanced forces on an object.
6. Explain what is meant by friction and describe both the beneficial effects and the problems caused by
friction.
7. Measure friction forces and their effects on an object’s motion.
8. Use force meters to measure forces on objects.
9. Describe weight as the gravity force on an object.
10. State the a force is measured in units called Newtons (N) and that 1N is the force needed to lift up 100g.

11. Calculate average speeds of objects using v = d/t. Whole number
calculations only are required.
12. Experimentally determine the speed of an object by measuring
both distance and time.
13. Describe the units of speed as m/s or km/h.
14. Draw a speed-time graph and recognise acceleration from the
steepness of the graph line.
15. Describe the journey of an object from a given speed-time graph.

Saturday, 13 March 2010

Unmix the table MAKING A GLOSSARY

WORD Ans Definition
1. Speed A. the unit of force
2. Acceleration B. a push or a pull
3. Deceleration C. when the forces that are in opposite directions are equal to each
other
4. Constant D. when the forces that are in opposite directions are not equal to
each other
5. Force E. a force, due to the earth, that acts downwards on all objects.
6. Newton F. The rate of decrease of speed
7. Balanced G. is good or helpful
8. Unbalanced H. the force which acts on an object in the forward direction
9. Thrust I. remains the same (doesn’t change)
10. Gravity J. a force that always opposes motion
11. Support K. a measure of the force due to gravity that acts on an object
12. Mass L. The rate of increase of speed
13. Weight M. A force due to the ground that prevents an object from falling

14. Friction N. the amount of matter in an object

15. Beneficial O. The rate at which distance is covered

MAKING A GLOSSARY
WORD Ans Definition
1. Speed A. The rate at which distance is covered
2. Acceleration B. The rate of increase of speed
3. Deceleration C. The rate of decrease of speed
4. Constant D. remains the same (doesn’t change)
5. Force E. a push or a pull
6. Newton F. the unit of force
7. Balanced G. when the forces that are in opposite directions are equal to each
other
8. Unbalanced H. when the forces that are in opposite directions are not equal to
each other
9. Thrust I. the force which acts on an object in the forward direction
10. Gravity J. a force, due to the earth, that acts downwards on all objects.
11. Support K. A force due to the ground that prevents an object from falling
12. Mass L. the amount of matter in an object
13. Weight M. a measure of the force due to gravity that acts on an object

14. Friction N. a force that always opposes motion

15. Beneficial O. is good or helpful


EF
FE
A CT
FO S
RC OF
E

WHAT CAN A FORCE DO?

Aim
to investigate the effects of forces

Equipment
Ping pong ball (1 per group)
Drinking straw (4 per group)
Cans or some other object suitable for the goal posts (4 per group)

Method - Part 1

1.By blowing through the straw apply force on the ball according to
the instructions given (the diagrams are there to help you)

2.For each exercise describe the response of the ball to the force
(what does the ball do?)


(i) The ball is stationery F v=0 Key
F = force
v = speed

The ball ___________________________________________________________

(ii) The ball is already moving in the direction of the force when the force is applied

F v

The ball ___________________________________________________________

(iii) The ball is already moving in the opposite direction to which the force is
applied
F v

The ball ___________________________________________________________

(iv) The ball is already moving sideways to the direction in which the force applied

F

v

The ball ___________________________________________________________

PING PONG SLALOM

1. This game involves setting up a slalom course (using objects from your pencil case)
on your desk.

2. Each player blows through a straw to control the motion of the ball so that it weaves
through the obstacles.

3. Each member of the group is timed using a stopwatch and given 3 turns.

4. The person with the lowest time wins the competition.


EFFECTS OF A FORCE

• A force is a push or a pull
• You cannot see a force but you can sometimes see the effects of a
force (what a force does).
• Forces can be either contact (eg. leaning on a desk) or non-contact
(eg. magnetic, gravity)

A force can:

1.Cause movement in an object that is initially stationery

2.Change the speed of an object (speed it up or slow it down)

3.change the direction of an object.

4.change the shape of an object.

5.hold an object up (or lift an object)


BA
UN LA
BA NC
LA ED
NC /
ED

Demo - lift force WHAT CAN A FORCE DO?

Ping pong ball

Hair dryer

Observation


BALANCED AND UNBALANCED FORCES

BALANCED FORCES Back Forward

Support force

Friction force Driving force speed stays the same
v
OR

speed equals ZERO
(STANDING STILL)
Force due to gravity

BALANCED FORCES ARE EQUAL AND OPPOSITE TO EACH OTHER

Draw diagrams showing all the forces acting in the following situations:

1.An aeroplane travels through the air in level flight at a constant speed.

2.A rock falls vertically with constant speed


ARE NOT EQUAL
UNBALANCED FORCES & OPPOSITE TO Back Forward
EACH OTHER

The object will speed up or it will slow down or change
direction
Support force

Friction force Driving force speed increases

in the forward direction


Support force
For an object that is
already moving in the
Friction force Driving force forward direction

speed decreases


Changing direction

Car B is on a “collision
course” car A’s path after the crash
with car A

Car B

Car A


Demo 1 BALANCED FORCES

• There are often several forces acting on an object.
• We see the effect of the combination of these forces often called the resultant force.
• When there is no resultant force we say that the forces are balanced.

Trolley Pulley
v

Hanging masses
Lump of plasticene
(balances friction)

Copy and complete the following sentences (words in the list below can be used more
than once):

If the object is stationery it will ____________ ____________ under

the influence of ___________ forces. If the object is moving at a ________
_________ then it will continue to __________ _____ ______ ____________
_____________ .

Word list: stationery remain steady balanced a speed with move

Demo 2 UNBALANCED FORCES

Trolley Pulley
v

Hanging masses

Copy and complete the following sentences (words in the list below can be used more
than once):

• If the object is moving in a forward direction at a steady speed, an unbalanced
force in the direction in which it is moving will cause it to _____________ .

• If the object is moving in a forward direction at a steady speed, an unbalanced
force in the opposite direction to which it is moving will cause it to
_____________ .

• If the object is moving forward and a force acts at right angles to the motion of the
object, describe the path of the object.

Word list: decelerate accelerate

Exercises FORCES AND MOTION

For each of the following situations:
1. describe the effect of the forces on the motion of the person or object in your own
words
2. draw the forces on the diagram if they have not already been drawn


Each team is as strong as the other

An incredible act of heroism ................. and all for a girl

Questions

1. Describe the motion of the helicopter when the
lift force is increased.

2. What happened to the helicopter when the skier
jumped out?

3. Describe the forces on the skier at the instant he
lands on the snow.

WHAT TYPES OF MOTION RESULT FROM THE FORCES DRAWN?

A ________________

B ________________

C _____________

Write a description of the types of motion
illustrated in the spaces (above)


A Accelerating
________________

B ________________

C _____________



A Accelerating
________________

B Constant speed
________________

C _____________



A Accelerating
________________

B Constant speed
________________

C Decelerating
_____________


FR
IC
TI
ON


Practical TAKE A DIVE

blue tack nylon


Results

Shape of Average time
Time taken to fall (s)
Parachute taken to fall (s)

Circular

Square

Rectangular

Triangular

Answer the questions (next slide) as full sentences


In the space below draw a force diagram showing all the forces acting on the
plasticene when it is dropping at a STEADY SPEED.


AIR FRICTION and SPEED

20 N
1500 N

1000 N

1000 N

Parachutist falling Parachutist falling rapidly at
slowly at first SO the time that the parachute
friction is small opens SO friction is large


36 km Space

1400 kmh -1

FELIX BAUMGARTNER
Smash the
sound
barrier
Earth

WHAT DO YOU KNOW ABOUT FRICTION?

Friction is a force that opposes motion. Can you give 5 examples of
useful friction and 5 examples of friction which is a nuisance to us.

“HOW USEFUL !!” “WHAT A NUISANCE !!”


FRICTION & FOOTWEAR
Aim
to find the relationship between the shoe design and the friction force between the
shoe and a flat surface.

Force meter
Force Shoe
This end is higher

Ramp inclined at
an angle ϴ

Background
When the shoe is pulled up the ramp, friction is acting in the opposite direction. If the
shoe is being pulled at a steady speed then the force of friction is equal to the pull
force. The pull force is read from the force meter and this measurement will
be equal to the friction between the shoe and the ramp.


Method
1. Set your bench up so that it is angled upwards (shown above).
2. Mark out a zone about 60 cm along the benchtop using a whiteboard marker. This
will be the zone within which you will pull the shoe along at a steady speed.
3. The reading on the force meter is taken and recorded next to the type of shoe that
was tested (in the table below).
4. Three readings of force are taken for each type of shoe and the average force is
calculated.
5. Steps 1 to 4 are repeated with at least 3 other different shoes.
6. The results are graphed.

Results

Type/
Average friction
description of Force applied (Newtons)
(N)
shoe

.
.


W
EI
GH
T

MASS AND WEIGHT

The mass of an object, m is a measure of the amount of matter in that object.

Units: kilogram, kg.

The weight of an object, Fw is a measure of the force due to gravity on that
object.

Units: Newton, N.

Practical: Finding the relationship between mass & weight

Spring balance (reading in Newtons)

Hanging masses (each mass, 50g)
Method
1. Add masses to the hook of the spring balance one mass (50g) at a time
2. Each time you add a mass measure the weight (force due to gravity) acting on the
mass and record it in the table below:

Results
Mass (g) 50 100 150 200 250 300 350 400 450

Weight (N)

Plot a graph of Weight against Mass and then write a conclusion


SO WHAT MAKES A GOOD GRAPH?

Now let’s see what a good graph looks like


Heading



Heading
Smooth curve/straight line
(of best fit) to complete
the graph



Heading
Smooth curve/straight line Axes labelled
(of best fit) to complete (with unit & quanitity)
the graph



Heading
the graph

Possibly a
key



Heading
the graph

Possibly a
key
Points
plotted as
crosses



Heading
the graph

Possibly a Linear scale
key
Points
plotted as
crosses


DRAWING A GOOD GRAPH

An example for all of us!!
Draw a distance - time graph using the values in the table:

t (s) d (m)

0 0

1 3

2 6

3 9

4 10

5 10

6 8

7 6

8 5

9 5




t (s) d (m)

0 0

1 3

2 6

3 9

4 10

5 10

6 8

7 6

8 5

9 5
0 1 2 3 4 5 6 7 8 9 10



t (s) d (m)

0 0 10

1 3 9

2 6 8

3 9
7
6
4 10
5
5 10
4
6 8
3
7 6
2
8 5
1
9 5
0 1 2 3 4 5 6 7 8 9 10



d (m)
t (s) d (m)

0 0 10

1 3 9

2 6 8

3 9
7
6
4 10
5
5 10
4
6 8
3
7 6
2
8 5
1
9 5
0 1 2 3 4 5 6 7 8 9 10



d (m)
t (s) d (m)

0 0 10

1 3 9

2 6 8

3 9
7
6
4 10
5
5 10
4
6 8
3
7 6
2
8 5
1
9 5
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10

1 3 9

2 6 8

3 9
7
6
4 10
5
5 10
4
6 8
3
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10

1 3 9

2 6 8

3 9
7
6
4 10
5
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10

1 3 9

2 6 8

3 9
7
6 x
4 10
5
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10

1 3 9 x

2 6 8

3 9
7
6 x
4 10
5
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10 x

1 3 9 x

2 6 8

3 9
7
6 x
4 10
5
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10 x x

1 3 9 x

2 6 8

3 9
7
6 x
4 10
5
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10 x x

1 3 9 x

8 x
2 6

3 9
7
6 x
4 10
5
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10 x x

1 3 9 x

8 x
2 6

3 9
7
6 x x
4 10
5
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10 x x

1 3 9 x

8 x
2 6

3 9
7
6 x x
4 10
5 x
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



d (m)
t (s) d (m)

0 0 10 x x

1 3 9 x

8 x
2 6

3 9
7
6 x x
4 10
5 x x
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)



A distance vs time graph
d (m)
t (s) d (m)

0 0 10 x x

1 3 9 x

8 x
2 6

3 9
7
6 x x
4 10
5 x x
5 10
4
6 8
3 x
7 6
2
8 5
1
9 5
x
0 1 2 3 4 5 6 7 8 9 10 t (s)

SP
EE
D


FORCES & GRAVITY


CALCULATING AVERAGE SPEED

distance travelled
Average speed =
time taken

This formula allows you to calculate the average speed when the distance and time
are known. It can be written using symbols:

v= d where v = average speed (in metres per second, ms-1)
t d = distance travelled (in metres, m)
t = time taken (in seconds, s)

Use this formula to calculate time when distance and speed are known

t= d
v

and this formula to calculate distance when speed and time are known

d= v x t

“Here’s an easy way of remembering the formulae” d
Just put your ﬁnger over the quantity you want to calculate and the
v t
formula appears

Examples
Calculate the average speed in each case:
1. A cyclist travels 100m in 5s.

2. A snail travels 1m in 200s.

3. An old man walks 300 cm in 2s.

Calculate the distance travelled in each case:
1. A car travels at 10ms-1 for 10s.

2. A Rocket in space travels 1500ms-1 for 60s.

Calculate the time taken in each case:
1. A car travels 100 m at an average speed of 10ms-1

2. A Rocket in space travels 30000 m at an average speed of 1500ms-1.


FRICTION - GOOD & BAD


MORE FRICTION


SPEED CALCULATIONS [Wignall & Wales]


GR
AP
M HS
OT
IO OF
N

“So what does speeding up look like on a speed - time
graph?”?
See for your self!
Draw two graphs for the
40000N
aeroplane taking off on a runway:
(a) a distance - time graph
(b) a speed - time graph 80000N 10000N

Distance (m) Time (s) Speed (ms-1)
0 0 0 40000N
10 1 10
30 2 20
60 3 30
100 4 40
150 5 50
210 6 60
280 7 70
360 8 80
450 9 90
550 10 100

distance - time graph speed - time graph
d (m) v (ms-1)

500 100

400 80

300 60

200 40

100 20

0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10
t (s) t (s)
Questions
1. Sketch and label a line on your speed time graph that shows greater acceleration.
2. Sketch and label a line on your speed time graph that shows deceleration.
The picture (above) shows the forces acting on the plane while it is on the runway.
3. Explain, in terms of the forces shown on the picture, why:
(a) the plane speeds up on the runway
(b) the plane remains on the runway before taking off

CONSTRUCTING A SPEED-TIME GRAPH Equipment:
lab trolley
Cello tape
ticker timer
ticker tape
Method scissors
30 cm ruler

Part 1: Making a ticker tape record of motion
1. Check that the power pack power switch is in the “off” position.
2. Switch the voltage control to 8V.
3. Connect the leads of the ticker timer to the AC sockets.
4. Thread one end of your ticker tape through the ticker timer so that when the
power pack is turned on and the tape is pulled through there is a trail of dots
produced. Test this with a short piece of tape before you thread your 1.5 m
length through.
5. Use Cello tape to attach the other end of the 1.5 m length of ticker tape to a lab
trolley.
6. Position the trolley and the timer as shown in the diagram.
7. Push on the trolley with enough force that it travels for at least 1.5 m after the
trolley has left your hand.

Timer 8V Power pack
On/Off

Trolley Ticker tape


Results
t (s) d (m) v (ms-1)
4.6 cm 0
0.015 0.15
0.1
0.046 0.46
0.2

An example of how to mark your tape and record your results

t (s) d (m) v (ms-1) t (s) d (m) v (ms-1)

0 1.1

0.1 1.2

0.2 1.3

0.3 1.4

0.4 1.5

0.5 1.6

0.6 1.7

0.7 1.8

0.8 1.9

0.9 2.0

1.0 2.1


Speed Speed - time graph for a falling mass
(ms-1)

1.1 s

0.5

time
0.2 0.4 0.6 1.6 s (s)

Summary UNDERSTANDING DISTANCE - TIME GRAPHS

distance

Standing still

Horizontal
Slowing down
Curving down

Constant speed
(the steeper the
line, the faster
the movement)
Straight

Speeding up Curving up

Saturday, 13 March 2010 time

Summary UNDERSTANDING SPEED - TIME GRAPHS

speed

Constant speed

Slowing down

Speeding up

time

Standing still Standing still

SPEEDING UP AND SLOWING DOWN

Consider the following speed - time graph of an object:

v (ms-1)
5
4 For each time interval
3 (labelled A, B and C)
2 complete the table below:
1 A B C

0 1 2 3 4 5 t (s)

Interval initial final Change in speed over how How much the
speed speed (final - initial speed) many speed changes in
seconds? one second

A

B

C

The ACCELERATION of the
object
A negative value is a
DECELERATION

ST
AR
TE
R S

DOUBLE TROUBLE


PLAYING ON WORDS


READING ABOUT NEWTON

Isaac Newton’s experience of an apple falling on his head encouraged him to think about forces.
He had ideas about gravity force that are still important today.
Newton was famous for his study of forces. He developed three laws which apply to forces.
Newton’s first law stated that an object will remain stationery of travel at a steady speed unless
acted upon by an unbalanced force. His second law stated that the object would accelerate in
the direction of the unbalanced force.
Newton knew that for any moving object there was often several forces acting together. The
forces would be unbalanced if when they are added together they do not cancel each other
out.
It is easy to work out the unbalanced force:


WHAT’S IN A NEWTON?

1. What is the shape of your graph?

2. What does your graph tell you is happening when you increase the amount of
mass (hanging) evenly?

3. How many Newtons of gravity force act on every 100 g mass?

4. Work out how many Newtons of gravity force would act on every kg of mass.

5. How many Newtons do you weigh on Earth?

6. The gravity force per kilogram on the moon is one sixth that of Earth. How many
Newtons would you weigh on the moon.

7. If you dropped an object on the moon, would you expect it to accelerate to the
ground as much as if you dropped it on Earth?

8. Why do you think the force of gravity on the moon is less than the force of
gravity on Earth?

9. When an object accelerates towards the ground, are the forces balanced or
unbalanced


PARACHUTING

1. Name two forces that act on a skydiver falling through the air.
Air friction/resistance/drag and gravity

2. What is meant by the term “terminal velocity”
the greatest speed achieved during a free fall

3. How does the air resistance on a falling object change as the object
speeds up?
It increases

4. Draw a picture showing the upward and downward forces on a skydiver
that is falling with terminal velocity.
drag

5. What force stays the same during skydiving?

gravity Gravity


Progress quizz - 3 Mar

1. instrument used to measure forces Force meter/spring scales

2. Name the unit of force Newton

3. Symbol for the unit N

4. 2 eg's of useful friction braking, parachuting, swimming, tyres

5. 2 eg's of friction which is a nuisance cars, planes, mechanical

6. Name the force that holds objects (on the ground) up support

7. Name the force (T...) that causes an object to speed up Thrust

8. 10 N ->, 2N <- ...... F's balanced/unbalanced Unbalanced

8N
9. Overall force

10. What happens to the air friction as an object falls faster. Increases


UNDERSTANDING THE DISTANCE-TIME GRAPH

A description of what the object is doing
during each time interval:
d (m)
5 A
4
3
B
2
1 A B C
C
0 1 2 3 4 5 t (s)

Distance-time graphs can show speed
Steady speed Stopped
1. Copy the graphs
2. Use the labels in the box to label them Acceleration Deceleration

d d d d

t t t t

QUICK QUESTIONS

1. Write the formula which allows you to calculate the:
(a) average speed when the distance and time are known

(b) time when the distance and average speed are known
(c) distance when the time and average speed are known
2. Use the information in the table below to draw a distance - time graph

t (s) d (m)

0 0

1 2

2 4

3 6

4 7

5 8

6 8

7 6

8 3

QUICK QUESTIONS
Describe the motion that is pictured in the following graphs for the intervals shown:

(a) A ___________________________________
d
B ___________________________________

C ___________________________________

D ___________________________________
A B C D t

(b) v
A ___________________________________

B ___________________________________

C ___________________________________

D ___________________________________
A B C D t


FORCES TO GRAPHS

1. What is the name of the force that drives objects in the forward
direction
2. Name the force that always acts in the opposite direction to the
object’s motion.
3. Name the force that slows down the motion of a parachute.
4. If an object is traveling at a steady speed, what can we say about the
forces acting on that object
5. If an object is speeding up what can we say about the forces acting on
that object
6. How does a force change the direction of an object?
7. Scientific word that means the same as 'speeding up"
8. What is a scientific word that means the same as "slowing down".
9. Sketch a distance time graph that shows an object traveling at a
steady speed.
10. Sketch a distance time graph that shows an object stationery.


PUTTING THINGS IN THE PICTURE

Study the graph below and answer the questions which follow:

d
Which section/s of the graph shows the object:
(a) at constant speed _______

C (b) stationery _______
(c) speeding up _______
A B D E (d) slowing down _______
(e) moving in the reverse direction _______

t

v
Which section/s of the graph shows the object:
(a) at constant speed _______
(b) increasing in speed steadily _______
(c) decreasing in speed _______

B D E (d) increasing in speed at an increasing rate
A
______
t

WORKING OUT ACCELERATION Extra 4 experts

Consider the following speed - time graph of an object:
v (ms-1)
5
4 For each time interval
3 (labelled A, B and C)
2 complete the table below:
1 A B C

0 1 2 3 4 5 t (s)

Interval initial final Change in speed over how How much the
speed speed (final - initial speed) many speed changes in
seconds? one second

A

B

C

Using the correct units of acceleration, write the acceleration of the
object during each time interval (in the space provided below):

A = ___________ , B = ____________ , C = ______________

EX
ER
CI
S ES

Student Notes Y10

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