Kelso High School
S3
Modified 2014
1
Speed and acceleration
You should remember the equation
v = d ÷ t
v is speed (velocity) in metres per second (m/s or ms-1)
d is distance in metres (m)
t is time in seconds (s)
You should be able to do calculations involving speed, distance and
time.
Example: A third year student ran the 100 m in
11.4 s. What was his average speed?
d
v
t
v=d÷t
= 100 ÷ 11.4
= 8.8 m/s
Example: A bat flew at 14 m/s in a straight
line for 3m. What distance did it fly?
d
v
d=vxt
= 14 x 3
= 42 m
t
Example: A spider travelling at a speed of 0.5
m/s ran 10 cm. How long did this take?
d
v
Careful d = 10 cm = 0.1 m
t
2
t=d÷v
= 0.1 ÷ 0.5
= 0.2 s
You should be able to change from kilometres, centimetres
and millimetres into metres.
1 km = 1 x 1000 m = 1000 m
1 cm = 1 ÷ 100 m = 0.01 m
1 mm = 1 ÷ 1000 m = 0.001 m
You should be able to change from hours and minutes into
seconds. 1 hour = 60 minutes = 3600 seconds
You should know the difference between average speed and
instantaneous speed.
The speed for the whole journey is the average speed
Average speed = total distance ÷ total time
The speed at one point in the journey is the instantaneous
speed
Instantaneous speed = short distance ÷ short time
You should be able to describe how to measure average and
instantaneous speeds
Measuring Average speed
Measure the total distance
travelled using a metre stick or
trundle wheel.
Measure the time taken to travel
this distance using a stop clock.
3
Average speed = total distance
total time
Measuring Instantaneous Speed
Measure length of card with ruler.
Measure time taken for card to pass
light gate with an electronic timer.
Instantaneous speed = length of card
time through gate
Accuracy when Measuring Speed
When speed is measured using a stopclock a less accurate
measurement is obtained then when using an electronic timer.
This is because of human reaction time.
You should know that acceleration is the rate of change of
speed.
You should be able to calculate the acceleration of a car.
Acceleration = change in speed = v - u
time taken
t
u is starting speed, v is final speed, t is time taken for speed
to change
Acceleration is measured in metres per second per second (ms-2)
4
Speed time graphs
You should be able to describe the motion of an object from
a speed time graph:0 to 6 seconds
speed increasing from rest
6 to 16 seconds constant speed
16 to 20 seconds speed decreasing to rest
uniform acceleration
zero acceleration
negative acceleration
You should be able to calculate the acceleration from a speed
time graph:-
5
0 to 6 seconds
a = v - u = 3 - 0 = 0.5 ms-2 6 to 16 seconds 0 ms-2
t
6
16 to 20 seconds
a = v - u = 0 - 3 = - 0.75 ms-2
t
4
You should be able to calculate the distance from a speed
time graph by working out the area.
0 to 6 seconds
d = area = ½ x 6 x 3 = 9 m
6 to 16 seconds
d = area = 10 x 3 = 30 m
16 to 20 seconds d = area = ½ x4 x3 = 6 m
Total distance = 9 + 30 + 6 = 45 m
Space and Satellites
The size of the Universe ranges from the very small to the very large and
travelling at conventional speeds, it would take many years to reach the
nearest star..
Planets in our solar system orbit around our closest star, the Sun.
Galaxies are huge and consist of billions of stars.
Light travels very fast, 300 million m/s.
A light year is the DISTANCE that light travels in one year.
Reflection and Refraction
Light reflects off mirrors and all surfaces.
A normal line is a dotted line drawn to cut through a surface at
angles.
right
The incoming angle is called the angle of incidence (i).
The outgoing angle is called the angle of reflection (r)
The angle of incidence is equal to the angle of reflection.
Curved reflectors bring light together at a focal point.
As light enters a glass block it changes direction
towards the normal line.
As light leaves a glass block, it changes direction away
from the normal line.
Refraction is the change in the speed of the wave as it changes material.
Concave lens
Convex lens
6
Satellites
Uses of satellites …
We need satellites to control many aspects of our daily life.
Global telecommunications
Environmental monitoring
Weather forecasting
behaviour.
‘Spying’ or monitoring human
A geostationary satellite orbits at a fixed height of around 36,000km. It
stays above the same geographical position.
7
Russia won the satellite space race
in 1957 by putting Sputnik into orbit.
Sputnik stayed in space for three
months before burning up on re-entry
into the Earth’s atmosphere.
Telstar was an American satellite.
It was the first satellite used to
broadcast television signals.
The international space station (ISS) is
the biggest satellite ever built.
Just three geostationary satellites are
needed for global telecommunications.
GPS stands for ‘Global Positioning
System’ and at least 4 GPS satellites
are used by Sat Nav car sytems.
The new generation of smaller satellites
is called ‘cube sat’ or ‘personal sat’.
8
Homework 1
The Mr Men were having a race.
(a) Calculate their average speeds from the following data. The race was over 100m.
(10)
(b) Why do you think Mr Forgetful’s speed is the value it is?
(1)
(c) Describe how you could measure the instantaneous speed of Mr Nosey as he
crossed the finish line
(4)
Mr
Mr Man
Man
Mr
Mr Skinny
Skinny
Distance
Average
Distance Time
Time Average
(m)
(s)
Speed
(s)
Speed (m/
(m/ s)
s)
(m)
100
65
100
65
Reason
Reason he
he came
came where
where he
he did
did
Mr
Mr Tickle
Tickle
30
30
Too
Too slim,
slim, got
got blown
blown over
over as
as itit was
was
windy
windy
Slowed
Slowed to
to tickle
tickle Miss
Miss Clever
Clever
Miss
Miss Clever
Clever
19
19
Had
Had to
to dodge
dodge Mr
Mr Tickle
Tickle
Mr
Mr Bump
Bump
45
45
Fell
Fell over
over Mr
Mr Skinny
Skinny
Mr
Mr Mischief
Mischief
25
25
No
No excuse
excuse but
but he
he looks
looks guilty
guilty
Mr
Mr Slow
Slow
180
180
It’s
It’s in
in the
the name
name
Mr
Mr Grumpy
Grumpy
50
50
Mr
Mr NonNonsense
sense
Mr
Mr Forgetful
Forgetful
25
25
Had
Had detention
detention with
with Mrs
Mrs Oliver.
Oliver. Was
Was
bang
bang out
out of
of order,
order, he
he never
never did
did it.
it.
Assnfh
Assnfh adhg.
adhg. OK,
OK, moving
moving on……….
on……….
00
Mr
Mr Nosey
Nosey
12
12
Won
by aa nose
nose
Won by
total marks 15
9
Homework 2 YOU MUST SHOW ALL WORKING
1. Usain bolt set three records in the 2008 Beijing
Olympics:
He ran the 100m sprint in 9.69s
He ran the 200m sprint in 19.30s
He and his Jamaican team ran the 4x100m relay race in 37.10s
Work out the average speed for each of these three races in m/s. You get
marks for showing the working
Extension: Work out the speed in km/h for the 100m sprint.
(6 + 2)
2. A greyhound can run at 17 m/s. How long would it take to cover 100 m? (3)
4. A snail took 3 hours and 20 minutes to travel 10 metres, what was its
average speed in m/s?
(3)
5. A car on a journey to Edinburgh has an average speed of 52 mph.
(a) What does mph stand for?
(1)
(b) Explain the difference between instantaneous speed and average speed.
(1)
6. Car A accelerates from 0 to 60 mph in 8.2 seconds, Car B takes 6.5
seconds . Which car has the greatest acceleration?
(1)
Total marks 15
10
Homework 3 YOU MUST SHOW ALL WORKING
1. Why is it better to use an electronic timer (or a computer) to measure
a short time period, e.g. a time less than 1s ?
(1)
2. What is the definition of acceleration ?
(1)
3. Write down the equation for acceleration.
Explain what each quantity is and what unit it is measured in.
(1)
4. Draw a sketch of the speed-time graphs showing acceleration, constant
speed and deceleration (negative acceleration).
(1)
5. How can a speed-time graph be used to calculate acceleration ?
(1)
6. How can a speed-time graph be used to calculate distance travelled ? (1)
7. A car accelerates from rest to 5ms-1 in 3s. It then travels at a constant
speed for a further 5s, then decelerates to rest taking 2s.
Draw a speed-time graph for this motion.
(3)
8. For the following speed-time graph ...
Speed (ms-1)
10
2
4
5
Time (s)
Calculate …
a) The final acceleration between 4 and 5s.
b) The distance travelled during the first acceleration period.
(3)
(3)
Total marks 15
11
Homework 4 Space
You many need to do further research to find the answers to some of the
following questions.
1. Light travels a distance of 300 000 000 meters in one second.
(i) A minute contains 60 seconds. How far will light travel in one minute?
(ii) An hour contains 3 600 seconds. How far will light travel in one hour?
(iii) A day contains 86 400 seconds. How far will light travel in one day?
(iv) A year contains 31 536 000 seconds. How far will light travel in one
year?
(4)
2. What was the first animal from Earth that went into space?
(1)
3. What was the first animal from to orbit the Earth?
(1)
4. What was the name of the first ever man-made satellite to orbit the Earth?
(1)
5. What was the name and nationality of the first man in space?
(2)
6. What year did this happen?
(1)
7. What was the name of the space mission which first landed man on the
moon?
(1)
8. What was the name of the craft which first landed on the surface of the
moon?
(1)
9. What year did man first walk on the moon?
(1)
10. Man has had a continuous presence in space on-board the International
Space Station since what year?
(1)
11. NASA is the United States of America’s government agency that is
responsible for space exploration. What does NASA stand for?
(1)
Total marks 15
12
Homework 6 Problem Solving
MERCURY
VENUS
EARTH
MOON
MARS JUPITER
SATURN
URANUS
NEPTUNE
Mass (1024kg)
0.330
4.87
5.97
0.073
0.642
1899
568
86.8
102
Diameter (km)
4879
12,104
12,756
3475
6792
142,984
120,536
51,118
49,528
Density (kg/m3)
5427
5243
5515
3340
3933
1326
687
1270
1638
3.7
8.9
9.8
1.6
3.7
23.1
9.0
8.7
11.0
4222.6
2802.0
24.0
708.7
24.7
9.9
10.7
17.2
16.1
Distance from Sun
57.9
108.2
149.6
0.384*
227.9
778.6
?
2872.5
4495.1
Orbital Period (days)
88.0
224.7
365.2
27.3
687.0
4331
10,747
30,589
59,800
Mean Temperature (C)
167
464
15
-20
-65
-110
-140
-195
-200
0
0
1
0
2
67
62
27
13
Gravity (N/kg)
Length of Day (hours)
Number of Moons
Use the data table above to answer the following questions:
1. Apart from Venus, What is the warmest planet? Why do you think that is?
2. What is the coldest planet? Why do you think that is?
3. Why do you think planet Venus has a higher mean temperature compared
to Mercury?
4. Which planet has the most moons orbiting it?
5. Which planets have no moons?
6. Which planet has the smallest diameter?
7. Compare the densities of Mercury, Venus, Earth and Mars with the densities of Jupiter, Saturn, Uranus and Neptune.
(i) Which group of planets has the highest density?
(ii) Why do you think this is?
8. What is meant by orbital period? (Hint: look at the value for Earth)
9. Which planet has the longest year and how long is it?
10. Which planet has a length of day closest to the Earth’s length of day?
11. Predict what distance from the sun Saturn is.
2
2
1
1
1
1
1
1
1
2
1
1
Total marks 15
13