PHYSICS
‘MASTER-BLASTER’
• Speed, Distance, Time
• Newton’s Laws (Forces)
• Work & Energy
• Radioactivity
• Stars & Planets
Topic: Speed, Distance, time
𝑺𝒑𝒆𝒆𝒅 =𝑫𝒊𝒔𝒕𝒂𝒏𝒄𝒆
𝑻𝒊𝒎𝒆
Speed measured in m/s
𝑨𝒄𝒄𝒆𝒍𝒆𝒓𝒂𝒕𝒊𝒐𝒏 =𝑪𝒉𝒂𝒏𝒈𝒆 𝒊𝒏 𝑺𝒑𝒆𝒆𝒅
𝑻𝒊𝒎𝒆
acceleration measured in m/s2
Speed and Acceleration
Question(s):
1. A car travels 3km in 250
seconds. What is its
average speed?
3,000 / 250 = 12 m/s
2. A cheetah stalks an
antelope, moving at
1m/s. It then darts
forward in pursuit of the
antelope. After 3 seconds
it is moving at 28 m/s.
What is its acceleration?
(28 – 1) / 3 = 9 m/s2
Topic: Speed, Distance, timeDistance-Time Graphs
Topic: Speed, Distance, timeSpeed-Time Graphs
Topic: Speed, Distance, time
Thinking Distance is
the distance travelled
while reacting.
Affected by tiredness,
alcohol etc.
Braking Distance is the
distance the car travels
after the brakes have
been pressed.
Affected by tyres, road
etc.
Stopping Distance (= Thinking Distance + Braking Distance)
Topic: Newton’s Laws (Forces)
• Newton 1:
“A body stays in a state of rest or uniform motion in a
straight line unless acted upon by an external force”
• Newton 2:
(Resultant) Force = mass x acceleration
• Newton 3:
“When body A pushes on body B, body B pushes back on A
with equal and opposite force”
Newton’s Three Laws
W = m x g
(g=10 on Earth)
Weight & Mass
Topic: Newton’s Laws (Forces)
Question:
1. What is Mr Pearson’s weight on Earth if has a mass of 83.5kg?
W = 83.5 x 10 = 835N
Earth Moon
20N 3.2N
no resultant force = no change (no acceleration)
Resultant force = 500-500 = 0N
Will travel at constant speed
Resultant force = 600 – 400 = 200 N
Will accelerate forwards
Resultant Force
Topic: Newton’s Laws (Forces)
Question:
The rocket has a
thrust of 200,000 N.
It has a mass of
18,000kg.
1. What is the rocket’s weight?
180,000N
2. What is its resultant force?
200,000 - 180,000 = 20,000N
3. Calculate the acceleration
a= f/m = 20,000/18,000 = 1.1 m/s2
When Weight = Air Resistance there is
no resultant force. Speed (velocity) doesn’t
change. Terminal Velocity.
Terminal Velocity
Topic: Newton’s Laws (Forces)
Topic: Newton’s Laws (Forces)Terminal Velocity - Specified Practical
Topic: Work & Energy
• When energy is transferred from one object to another,
scientists say “Work is done”.
• Different types of energy are: kinetic, thermal, gravitational,
elastic, sound.
• The amount of work done can be calculated by:
Work Done = Force x Distance
Work Done
Question:
How much work is done by the
man pushing the box?
W.D. = F x D
W.D. = 10 x 2
W.D. = 20 Joules
Gravitational Potential Energy (GPE) Kinetic Energy (KE)
GPE = m g h KE = ½ m v2
(g=10)
Kinetic & Gravitational Energy
Topic: Work & Energy
Question:
A cyclist has a mass of 68kg and is cycling at
8 m/s. She then rides up a hill to a height of 3m.
1. What is her KE at the start?
KE = 0.5x68x82 = 2,176 J
2. What is her GPE at the top?
GPE = 68 x 10 x 3 = 2,040 J
3. Why has she got less GPE than KE?
Energy lost as heat because of friction
• Force = spring constant x extension F = kx
• Bigger spring constant (k) = stiffer spring
• Specified Practical
Springs
Topic: Work & Energy
[H tier] Work done in stretching a spring is the elastic energy that gets stored in the spring. It is ½ x force x extension:
• W.D. = ½ F x
• W.D. is also area under the force –extension graph
WD
• Force = spring constant x extension F = kx
• Bigger spring constant (k) = stiffer spring
Springs
Topic: Work & Energy
[H tier] Work done in stretching a spring is the
elastic energy that gets stored in the spring. It is:
• W.D. = ½ F x
• W.D. is the area under a force–extension graph
WD
Springs – Specified Practical
Topic: Work & Energy
Vehicle Safety & Efficiency
Topic: Work & Energy
Efficiency:
• Aerodynamic losses:
streamlined designs.
• Rolling resistance: correctly
inflated tyres & tyre material that
doesn’t heat when squashed.
• Idling losses: stop/start systems
• Inertial losses: lighter cars.
Car Safety:
These increase the distance
taken to stop. This reduces
the force on the person (by
doing work over a larger
distance)
Topic: Radioactivity
• Isotopes are atoms with the same number of protons but
different numbers of neutrons. E.g.
• Some isotopes are stable (last forever).
• Some isotopes are unstable and decay at random.
Atoms
49𝐵𝑒
410𝐵𝑒
This atom has:
9 nucleons
4 are protons
5 are neutrons
Nucleon number
Proton number
• Unstable isotopes can decay via alpha, beta or gamma.
• Alpha is a helium nucleus ( 24𝐻𝑒 or 2
4𝛼 )
• Beta is a fast electron ( −10𝑒 or −1
0𝛽 )
• Gamma is an electromagnetic wave (g)
• Ionising (most to least): alpha, beta, gamma
• Penetration and stopping:
a, b, g and Decay
Topic: Radioactivity
92235𝑈 → 90
231𝑇ℎ + 24𝐻𝑒
614𝐶 → 7
14𝑁 + −10𝑒
Background radiation comes
from many sources.
Radon gas comes from rocks.
Medical uses such as imaging
and treatment
Nuclear waste storage is a problem
because it stays radioactive
for thousands of years.
Uses of Radioactivity
Topic: Radioactivity
“Half-life is the time taken for the number of radioactive nuclei
to reduce to one half of its value”
Specified practical:
decay dice
Dice and Half-life
Topic: Radioactivity
Questions:
1. What is the graph’s half-life?
2. A sample has an activity of
600Bq and half-life of 3 days.
What’s the activity after 12
days?
600 300 150 75 37.5
Dice Specified Practical
Topic: Radioactivity
Topic: Stars & Planets
• Earth – moon
• Earth – Sun
• Solar System
• Sun – near Stars
• Galaxy
• Galaxy – Galaxy
• Universe
Scale of the Universe
Distances are measured in:
• Kilometres (km) e.g.
300,000km Earth to Moon
• Astronomical Units (AU)
e.g. Jupiter is 5.2 AU from
the Sun.
1AU = distance from sun to Earth
• Light Years (LY) e.g. Milky
Way is 100,000 LY wide
1 LY = distance light travels in one
year
Forming the Solar System
Topic: Stars & Planets
Gravitational forces cause the
gas/dust cloud to shrink,
creating.
This gas cloud has come from
a dead, large star that went
supernova. This means it
contains many heavy
elements.
The centre becomes the Sun.
Around this, left-over gas/dust
forms the planets.
Rocks gather closer to the Sun
(rocky planets) and gases
further away (gas planets).
The Solar System
Topic: Stars & Planets
Star; Planets; Dwarf Planets; Moons; Asteroids; Comets
Lives of Stars
Topic: Stars & Planets
Hertzsprung-Russell Diagram [H-Tier]
Topic: Stars & Planets
Hertzsprung-Russell Diagram [H-Tier]
Topic: Stars & Planets
1
2
3
Revision Planning – Know vs Do!• Every topic: what is knowledge and what is doing
• Knowledge is revision (flash cards, look-cover-check)
• Doing is practising (past questions – get feedback)
Newton’s Laws
KNOW
Quote the three laws
Know difference between weight and mass
No resultant force = no acceleration
Describe cake case experiment
DO
Calculate resultant force
Calculate using F=ma
Calculate using weight = mass x gravity
Apply the three laws to situations (eg rockets)
Exam Paper Breakdown
• 40% Numeracy / Calculations
• 20% Practical skills / knowledge
• 1x ‘6 mark’ QER question
• 40% ‘AO1’ – knowledge of physics (KNOW)
• 60% ‘AO2/3’ – applying & using physics (DO)
• Typically, a question from each topic area
Top Five Tips for success!
• Organise a revision timetable.
• Little & often with planned breaks and rewards.
• Find out what you don’t know or can’t do and
focus on these areas. Ask for help.
• Use a range of techniques, that suits you.
• Suitable environment to learn without distractions
(turn phone off and wait for a break/reward).
Be positive, it is never too late to
make a difference!