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What is the difference between speed and velocity?
Speed has a magnitude velocity has a magnitude and direction
The units for speed are:
m/s
4km is how many meters
4000m
2km is how many meters
2000m
300km is how many meters
300 000m
The units for velocity are:
m/s
The units for acceleration are :
m/s2
A car has a mass of 200kg and is travelling at 20m/s when it comes to a sudden stop taking 0.5 seconds what is its deceleration?
40m/s2
A man runs from his home to work this is a distance of 2km it takes 720 seconds. What speed is he running at?
2000/720 = 2.78 m/s
At a local snail race Sammy the snail is travelling at 0.002m/s the race from start to finish is 3 meters how long does it last?
3/0.002 = 1500 seconds
A block falls from the top of a sky scraper it takes 4 seconds to hit the ground the acceleration is 10m/s2. What is its final velocity?
10 x 4 = 40m/s
A flat horizontal line on a distance time graph represents:
A stationary Object
A diagonal line on a distance time graph represents:
An object moving at constant speed
A flat horizontal line on a velocity time graph represents:
Constant speed
A diagonal line on a velocity time graph represents:
Acceleration
The area under a velocity time graph represents:
Distance
The gradient of a velocity time graph represents:
Acceleration of an object
The gradient of a distance time graph represents:
The speed of an object.
When a force is applied to an object to move the force needs to be �..
bigger than friction
For an object to sit still on a table the weight of the object must equal the �.
reaction force from the table.
When an object has a resultant force it will �.
accelerate in the direction of the resultant force
How do we find the resultant force on an object
Subtract the smallest force from the largest force.
Reaction force from a table or water always acts �
upwards
Friction always acts in the:
Opposite direction to the movement of the object.
If the force of friction is bigger than the forward force on a car this means �.
the car is slowing down (NOT GOING BACK)
If the force of Air resistance/friction on a parachutist is greater than gravity this means it is �.
slowing down (NOT GOING BACK UP)
Thinking distance is
The distance travelled by the driver from when he sees the hazard and touches the brake
Braking distance is �.
How far the driver travels from when he presses the brake and comes to a stop.
Write the equation that links force acceleration and mass
Force = Mass x Acceleration
A car accelerates at 4m/s2 and has a mass of 1500kg what force is the engine providing?
6000 N
A car brakes and decelerates at 6m/s2 the braking force is 9000N. What is the cars mass?
1500 Kg
When the engine thrust is equal to the force of friction the car is �.
Travelling at a constant speed.
Friction always causes and object to
Heat up
When braking the tyres and brakes will
Heat up
What factors affect thinking distance
1) Drugs and Alcohol 2) Tiredness 3) Distractions e.g. Mobile phone
What factors affect braking distance
1) Worn Brakes & Tyres 2) Road Surface 3) Weather conditions e.g. Wet or Icy roads
Stopping distance is
The distance travelled by the driver from when he sees the hazard until he stops.
Stopping distance =
Thinking distance + Braking distance
On a force diagram the gravity arrow should point �
Downwards
The units for Force is �
Newtons
As an object falls its velocity �
increases
As an object falls its momentum �
increases
What factor affects both braking distance and thinking distance �.
Speed
As surface area increases air resistance �.
increases
A sky diver with less surface area will fall ��
faster
Resultant force is always in the direction of
travel
Weight =
mass x gravity
The units for weight are
Newtons
The units for mass are
kg
If a man has a mass of 75 kg on earth (g=10N/kg) what is his weight?
750 Newtons
Kinetic Energy =
1/2 x Mass x (speed)2
Kinetic Energy is measured in:
Joules
Sarah is running at 4m/s and has a mass of 55kg what is her kinetic energy?
440 Joules
A car has a mass of 1200 kg and is travelling at 20m/s what is its kinetic energy?
240 000 Joules
Work done =
Force x Distance
If a box is pushed with a force of 200 Newtons for 8 metres how much work is done?
8 * 200 = 1600Joules
Work done is measured in �
Joules
1800 Joules of energy is used to push a box 6 meters how much force is applied?
Force = Workdone/ distance = 1800 J/6 = 300 newtons
3 people are sat in a car travelling at 20 m/s. Their masses are Person A = 60 kg person B = 85kg and person C = 67 kg Who has the most momentum and why?
Person B because momentum = mass x velocity and person B has the most mass.
Power =
Energy / time
Power is measured in
Watts
200 Joules is used to lift an object 4 meters in 5 seconds. How much power is needed?
Power = Energy/time = 200/5 = 40W (The 4 meters does not matter)
Gravitational potential energy =
mass x gravitational field strength x height
A man climbs to the top of a diving board which is 6 meters from the ground he has a mass of 65 kg and g=10N/kg. What is his gravitational potential energy?
3900 Joules
Momentum =
mass x velocity
The units for momentum are
kgm/s
A hedgehog rolling down a hill has a mass of 1.5 kg and a velocity of 5m/s what is its momentum?
7.5 kgm/s
What equation links force change in momentum and time?
Force = Change in momentum/time
How does a seat belt work?
When a crash occurs the seat belt stretches this means that it takes longer for the person to slow down. If the time to slow down is longer the change in momentum will be slower therefore the impact force will be less. This means it is less likely for the person to be injured.
Why does a children's playground have rubber tiles for a floor cover.
When a child falls on the rubber tiles they flex and bend this means that it takes longer for the person to slow down. If the time to slow down is longer the change in momentum will be slower therefore the impact force will be less. This means it is less likely for the person to be injured.
Why is a vase wrapped up in polystyrene?
If the vase is dropped the polystyrene will compress and break this means it takes longer for the vase to slow down. If the time to slow down is longer the change in momentum will be slower therefore the impact force will be less. This means it is less likely for the vase to break.
A car has a momentum of 21 000kgm/s it has a mass of 1500 kg what is its velocity?
14m/s
A car has a momentum of 30 000kgm/s and is travelling at 40m/s what is its mass?
750 kg
How is an object made statically charged?
By rubbing two insulators together electrons move from one insulator to the other. This leaves one object negatively charged and the other positively charged.
A positive charge and a negative charge will
Attract each other
Two positive charges will
Repel each other
Two negative charges will
Repel each other
When electrons leave an object this object is now �?� charged
Positively charged
When electrons move onto an object this object is now �.?.... charged.
Negatively charged
When two plastic rods (A and B) of different materials are rubbed together what happens?
The electrons from rod A move onto rod B. This leaves rod A positively charged and rod B negatively charged.
Ammeters are always connected in �.
Series
Voltmeters are always connected in �.
parallel
3 resistors are connect in series they are 50 ohms 20 ohms and 30 ohms what is the total resistance?
100 Ohms
In a series circuit there are three ammeters the first ammeter reads 0.4 amps what do the other two read?
0.4 amps
In a series circuit current is �.
the same everywhere.
There are three bulbs in a series circuit the potential difference across each bulb is 6 volts what is the total potential difference provided by the battery?
18 volts
How is the potential difference calculated in a series circuit?
By adding the potential difference across each component together.
When the temperture of a resistor or wire is increased what happens to the resistance?
It increases
The higher the resistance of a resistor or bulb the ��... current that flows through it?
Less
A battery provides a potential difference of 12 volts in a parallel circuit what potential diffference goes down each branch?
12 Volts
0.2 Amps flows through 1 branch of a parallel circuit 0.4 Amps flows through another branch what current flows out of the battery?
0.6 Amps
In parallel the potential difference down each branch is ��
the same
In parallel the total current equals �.
the current in each branch added together
What colour is the earth wire ?
Green and Yellow
What colour is the live wire?
Brown
What colour is the neutral wire?
Blue
What is the earth wire used for?
Should the live wire break and touch the side of the case the appliance would become electricaly charged this is dangerous as if you touch it you will receive a shock. However the earth wire is attached to the case and as it is more conductive than the human body charge will flow away through it preventing a shock.
How does a fuse work?
If there is a sudden surge of current in the live wire the fuse will melt due to the high current breaking the circuit. This prevents humans from receiving an electric shock and fires.
Why is it bad to attach many plugs into one plug socket using adapters?
The plug will draw too much current over heat and potentially cause fires.
The live wire is connected to the ��� pin
right
The neutral wire is connected to the ���.. Pin
left
The earth wire is connected to the �� pin
top
Mains electricity has a frequency of �..
50 Hz
Mains electricity has a voltage of
230 V
The wavelength of a wave can be found by measuring
crest to crest / trough to trough/ one identical point to the next identical point
The time period of a wave is
the amount of time taken for one wavelength to pass
Frequency =
1 / Time Period
Frequency is measured in ���..
Hz
Time is measured in ��.
Seconds
Time period =
1/ frequency
To convert from milli seconds to seconds you must �
divide by 1000
to convert from km to m you must
multiply by 1000
to convert from kJ to J you must
multiply by 1000
to convert from mA to Amps you must
divide by 1000
to convert from hours to seconds you must
x 60 x 60 or x 3600
to convert from minutes to seconds you must
x 60
25 milli seconds I how many seconds
0.025 Seconds
30 km is how many meters
30 000 m
12 mA is how many Amps
0.0012 Amps
3 mA is how many Amps
0.003 Amps
How many Joules is 20kJ
20 000 Joules
How many seconds is 20 minutes
1200 seconds
How many seconds is 3 hours
10800 seconds
An electricity supply has a time period of 5 ms what is its frequency ?
200 Hz
An electricity supply has a time period of 20 ms what is its frequency ?
50 Hz
An electricity supply has a time period of 0.5 seconds what is its frequency?
2Hz
An unstable nuclei becomes stable by?
Emitting Radiation
The nucleus of an atom is made up of?
Protons and neutron
What is the charge of a nucleus?
Positive
What are the sources of background radiation?
Radon Medical Ground Buildings Food & Drink Cosmic Rays
Most of the mass of an atom is located in the________?
Nucleus
Alpha particles are fired at a piece of gold foil (Rutherford Experiment) it is observed that the particels are deflected .Why?
The positively charged alpha particles are deflected by the positively charged nucleus because like charges repel.
An alpha particle is made up of?
2 protons and 2 neutrons
A beta particle is?
An electron
Gamma is?
An electromagnetic wave
What is an isotope?
An isotope of an element has the same number of protons but a different number of neutrons.
An atom has an atomic number of 42 and a mass number of 96. How many neutrons does it have?
54
An unstable nuclei has mass number 228 and atomic number 90. It decays by alpha emission. What is its new mass number and atomic number
Mass number: 224. Atomic number 88
An unstable nuclei has mass number 40 and atomic number 19. It decays by beta emission. What is its new mass and atomic number?
Mass number: 40. Atomic number: 20
Does the emission of gamma radiation change the mass number or atomic number? Why?
No. Gamma radiation is uncharged and has no mass.
Alpha radiation can be stopped by��
�a thin sheet of paper
Beta radiation can be stopped by�.
about 5mm of Aluminium or a few mm of Lead
Gamma radiation can be stopped by�.
thick Lead (several cm) or concrete (>1m)
The range of gamm radiation in air is��
unlimited
The range of alpha radiation in air is�..
about 5cm
The range of beta radiation in air is�.
about 1m
Alpha and beta radiation are both deflected by electric and magnetic fields which is defelcted more and why?
Beta is deflected more as it has a lower mass than alpha.
Which type of radiation can not be deflected by an electric or a magnetic field?
Gamma radiation
The process by which an atom loses electrons is called?
Ionisation
Why is ionisation from radioactivity dangerous?
As it can damage or kill living cells and damage genes/
The half life of an isotope is the�.
average time it takes for the number of nuclei of the isotope in a sample to halve
A sample starts with 1000 nuclei and has a half life of 20 mins. How many nuclei will be left after one hour.
125 nuclei
What type of radiation would be suitable for automatic thickness monitoring of Aluminium foil?
Beta
Radioactive tracers should be what type of radiation
Beta and Gamma
How long should the half life be of a radioactive tracer be?
Long enough to monitor the patient but no longer
A nuclear reactor uses the process of _____________ to release energy.
Nuclear fission
What is nuclear fission?
It is the splitting of a nucleus into two approximately equal fragements and a few neutrons.
Each fission event causes further fission events. What is this called?
Chain reaction
Control rods are used to keep the chain reaction in a nuclear reactor under control. How do they do this?
They absorb neutrons and therefore reduce the number of atoms splitting.
Are the nuclei involved in nuclear fission heavy or light?
Heavy
Are the nuclei involved in nuclear fusion heavy or light?
Light
What is nuclear fusion?
Nuclear fusion is the joining or light nuclei together into larger heavier nuclei
Nuclear fusion takes place in the Suns core. What is released?
Energy
Nuclear fusion requires very high temperatures. True or False
TRUE
In the formation of a star particles of dust and gas are brought together by�..
gravity
How does a star release energy?
From the process of nuclear fusion of Hydrogen into Helium
Why is a star stable?
The force of gravity is balanced by the force of the radiation from its core
After the main sequence what will happen to a star about the size of the Sun?
It will swell and cool becoming a RED GIANT fusion of He forms heavier elements. The star then collapses in under its own gravity and becomes a hot dense WHITE DWARF. This then cools to a a BLACK DWARF.
After the main sequence what will happen to a star much bigger than the Sun?
It will swell and become a RED SUPER GIANT which will then collapse. The star will then explode as a SUPERNOVA. There will now be a dense NEUTON STAR or if its mass is high enough a BLACK HOLE.
Where are the heavier elements formed (heavier than Iron)?
In a supernova
What does the mass number of an element tell us?
The number of protons and neutrons
What does the atomic number tell us?
The number of protons (sometimes called the proton number)
What is the difference between Uranium 235 and Uranium 238
U 238 has 3 more neutrons than U 235
What is the difference between Plutonium 238 and Plutonium 239?
Pu 239 has 1 more neutron than Pu 238
Give a good example of the half life of a radioactive tracer used to study the human body?
5-10 days
Give a good example of the half life of a radioactive tracer to measure the growth of a plant?
28 days
What is the charge on a proton
Positive
What is the charge on an electron
Negatively charged
What is the charge on a neutron
No Charge
What is the mass of a proton
1
What is the mass of a neutron
1
What is the mass of an electron
1/2000 or negligble
What is the charge on an alpha particle
Positive
What is the charge on a beta particle
Negatively charged
What is the charge on a gamma ray
It has no charge.
Explain why fission is a chain reaction?
Uranium or Plutonium splits due to the introduction of a neutron. When they split they produce more neutrons which cause other uranium or plutonium atoms to split.
What is the fuel for fission
Uranium or Plutonium
What is the lightest element used in nuclear fusion?
Hydrogen (H + H fuses to make Helium)
A source of raidation has a half life of 3 days. To begin with there are 2000 nuclei. How many are left after 9 days?
250 Nuclei
Describe the plum pudding model for an atom
"An atom is made up of a sphere of positive charge with small negative charges dotted around inside it ""like plums in a plum pudding"""
Describe Rutherford's experiment and his findings.
Rutherford carried out an experiment which involved firing alpha paricles at a thin sheet of gold atoms. 1) Rutherfore expected to find the mass evenley distributed. 2) He found that most of the alpha particles travelled through the foil 3) Some were deflected by a small amount others by much more 4) The closer they were to the centre of the atom the more they were deflected 5) A few alpha particles had a direct course through the centre of the atom these were deflected back. 6) This showed that the majority of the mass is concentrated at the centre of the nucleus. 7) It showed the nucleus was positively charged and negative charges must orbit the nucleus.
Name three natural sources of background radiation
Cosmic rays, radon gas, rocks and building materials, Food/crops
Name two man made sources of background radiation
Medical X rays or Nuclear Industry
"If you are exposed to more than 50 units of radiation you have a high risk of getting cancer. If James takes a flight to New York he will be exposed to 5 units of radiation. Would you advise him to take the flight?
Yes) As 5 units is 10 times less than the dangerous level. OR No) As any exposure to radiation can be dangerous.
What are the units of charge?
Coulombs
What is the unit of current?
Amp / Ampere
The unit of potential difference is?
Volts
What is used to measure potential difference ?
Voltmeter
What is used to measure current?
Ammeter
What is the most important thing to do in an exam?
RTFQ - Read the full question!!
When answering a question using numbers what should you do?
Identify the varibles e.g (Force mass acceleration). Identify the correct equation to use and the equation triangle. Write down the numbers for each variable. Use your calculator to find the answer.