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158 Cards in this Set
- Front
- Back
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What is weight? |
A force that acts towards the centre of the Earth |
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What do all forces have? |
-A magnitude -A direction -measured in newtons (N) |
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What is a vector quantity? |
Quantities that have both a size and a direction |
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Are forces vectors or scalars? |
Vector |
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What does a longer arrow represent? |
A larger force |
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What does the weight of a person depend on? |
Their mass |
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What does mass measure? |
The amount of matter in something (has no direction) |
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What are quantities called that don't have a direction called? |
Scalar quantities |
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What are some other scalar quantities? |
-Distance -Speed -Energy -Time |
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What is displacement? |
The distance covered in a strait line by an object with no direction |
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Is the displacement of an object usually smaller or larger than the distance travelled? |
Less |
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Why will a cyclists velocity change even if they maintain the same speed? |
Velocity is speed in a particular direction so the velocity can change if the cyclist is changing direction even if they maintain the same speed. |
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What are some other vector quantities? |
-Acceleration - a measure of how fast velocity is changing -Momentum - a combination of mass and velocity |
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What is the equation for speed? |
distance Speed = ------------- time |
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What are the units for speed? |
-m/s -km/s |
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What is the instantaneous speed? |
The speed at a particular point in a journey |
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How can you measure the speed of an object in the lab? |
Light gates (more accurate then a stopwatch) |
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What does a horizontal line tell you about the object on a distance/time graph? |
Means the object is stationary (Its distance from the starting point is not changing) |
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What does a strait, sloping line tell you about the object on a distance/time graph? |
Means the object is travelling at a constant speed |
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What does a steeper line tell you about the object on a distance/time graph? |
The faster the object is travelling the steeper the line |
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How do you calculate speed on a distance/time graph? |
The speed is calculated from the gradient of the line |
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A falcon flies at 50 m/s for 7 seconds. How far does it fly? |
50 x 7 = 350 m |
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What is the equation for acceleration? |
change in velocity Acceleration = ------------------------- time taken |
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What is the abbreviated form of the equation for acceleration? |
v-u a = ------ t |
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What is a change in velocity called? |
Acceleration |
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Is acceleration a vector or scalar quantity? |
Vector quantity because it has a magnitude and a direction |
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What are the units for acceleration? |
m/s 2 |
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What does deceleration mean? |
When an object is getting slower |
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How can you show the changing of velocity? |
Velocity/Time graph |
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What does a negative velocity show? (a line below the horizontal axis) |
The object is moving in the opposite direction |
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How do you calculate the distance travelled from a graph? |
You work out the different areas of the graph then add them all together -e.g. split them up into squares and triangles |
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What is a resultant force? |
The sum of the average of all the forces acting on the object |
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What do you call the forces if they equal to zero? |
Balanced |
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What do you call the forces if they are not equal to zero? |
Unbalanced |
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What can Newton's first law be written as? |
-A moving object will continue to move at the same speed and direction unless an external force acts on it -A stationary object will remain at rest unless an external force acts on it |
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What is the centripetal force? |
The resultant force that causes the change in direction -Friction -Gravity |
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How can weight be measured? |
Force meter |
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What is the gravitational field strength on Earth? |
10 N/Kg |
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How do you calculate the weight of an object? |
Weight (N) = Mass (kg) x Gravitational filed strength (N/Kg) W = m x g |
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What forces are acting on a falling body? |
-Air resistance -Weight -Gravity |
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What is Newton's second law of motion? |
-Factors that accept the acceleration of an object -The size of the force -The mass of the object |
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How do you calculate force? |
Force (N) = mass (kg) x acceleration (m/s 2) F = m x a |
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What is the inertial mass of an object? |
The force on it divided by the acceleration that force produces |
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What is an equilibrium situation? |
When nothing is moving because the forces are equal -Dog pulling on rope - rope pulling back on dog |
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What is an action-reaction force? |
According to Newton's third law, for every action force there is an equal (in size) and opposite (in direction) reaction force. |
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What is the difference between balanced and action-reaction forces? |
-Action reaction forces act on different objects -Balanced forces all act on the same object |
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Describe the action reaction forces when a ball hits the ground |
As the ball exerts a force on the ground the ground is exerting a force back at the ball. The sizes of these forces are the same but so not have the same effects as the ball will bounce off the ground but the ground won't bounce off the ball. |
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What is the formula for momentum? |
Momentum = mass x velocity |
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Explain why are motorcycle travelling at 30 m/s has less momentum than a car travelling at the same velocity |
The car has a higher mass therefore using the equation you can see that the momentum of the car would be significantly higher than the momentum of the motorcycle even if they have the same velocity |
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What is the equation for momentum and acceleration? |
mass x change in velocity Force = ------------------------------------ time |
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Is v the initial or final velocity? |
-Final velocity -U is the initial velocity |
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What is conservation of momentum? |
When moving objects collide the total momentum of both objects is the same before and after the collision- as long as there are no external forces acting |
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What is thinking distance? |
The time it takes for the driver to react to a situation |
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What is the braking distance? |
The time it takes for the brakes to slow the car down to a halt |
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What is the equation for stopping distance? |
Stopping distance = thinking distance + braking distance |
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What is reaction time? |
The time between a person detecting a stimulus and their response |
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How can response times be measured? |
Using -computers -electric circuits These can measure the time between a stimulus and a response |
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What can increase reaction times? |
-Drinking -Drugs -Mobile phones -Tiredness -Sickness |
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Why is friction between the road and tyres important? |
-If the brakes or tyres are worn they create less friction this means they don't slow the vehicle as quickly -If the road is wet or has gravel loose on it there is less friction and the braking distance is increased |
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Which one has a greater braking distance and why? -Heavy / light vehicle |
-If a vehicle has more mass, more force is needed to decelerate it -So if the same amount of friction is used to stop a vehicle, a heavier vehicle will travel further than a lighter one |
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What does the force needed for acceleration depend on? |
-The mass of the vehicle -The size of the acceleration |
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Why is a crumple zone useful for the safety of drivers? |
-Crumple zones are built into the front of cars -If the car hits something it takes a little time for this crumpling to happen so the deceleration of the car is less and the force on the car is also less than if it had a more solid front -Therefore, the passengers of the car are more safe because the crumple zone absorbs most of the energy transferred from the collision |
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What do airbags do? |
Increase the time it takes for a person's head to stop in a collision -this reduces the force on them |
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How is energy transferred between different stores? |
Energy can be transferred between different stores. When an electric kettle is used to heat up water, energy transferred to the kettle by electricity ends up as a store of thermal energy in the hot water. As the hot water is at a higher temperature than the kettle and the surroundings, some energy is transferred to these things by heating. energy can also be transferred by light and sound. |
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How can we represent energy transfers in diagrams? |
Sankey diagrams |
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What happens to the total amount of energy when energy is transferred? |
The total amount of energy transferred by the system is the same as the energy put into the system. Energy can't be made or destroyed so the amount of energy stayed the same. |
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Describe the changes in energy stores when a car accelerates. |
When a car accelerates the electrical and kinetic energy stored inside the engine and the wheels is transferred into thermal energy, sound energy and kinetic energy. The thermal and sound energy is wasted energy and the kinetic energy is useful energy which is used to power the car. |
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Describe the energy stores as a ball rises and then falls again. |
When a ball rises it gains gravitational potential energy and kinetic energy which is then transferred into kinetic energy which increases as the ball falls. However the gravitational potential energy decreases as the ball falls. |
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List the ways in which energy can be transferred. |
-Thermal energy -Gravitational potential energy -Kinetic energy -Sound energy -Electrical energy -Chemical energy |
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What does efficiency mean? |
Efficiency is a way of describing how good a machine is at transferring into useful forms. On an efficiency scale the higher the number the more efficient the object is. |
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How do we calculate the efficiency of an energy transfer? |
Efficiency (J) = useful energy transferred from the device / total amount of energy supplied to the device. |
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How can we reduce unwanted energy transfers in machines? |
Lubrication. Lubrication stops friction between objects and this stops the object getting hot. whenever two moving parts touch each other, friction causes them to heat up. The thermal energy stored in the hot machine is transferred to the surroundings by heating, which dissipates the energy. |
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Explain why it is harder to pedal a bike if the chain needs oiling? |
If the chain on a bike needs oiling then it is wasting useful energy by sound energy and thermal energy. |
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When you pedal a bike how is the wasted energy transferred to the surroundings? |
When you move the pedals the kinetic energy stored in the pedals is transferred to the surroundings through thermal energy and sound energy. |
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Explain how the efficiency of a bike can be increased. |
The efficiency of a device can be increased by reducing the amount of wasted energy. For mechanical processes, such as engines, this can mean reducing friction. Or finding a way to make sure all the fuel going to the engine is burned. Or find a way to use the energy transferred by heating that would be otherwise wasted. |
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Explain why adding oil to the door hinges makes the door easier and quieter to open. |
When you oil the hinges of a door frame you decrease the friction and therefore you also decrease the thermal energy and the sound energy which is not useful energy transferred from the door into the surroundings. Therefore if you decrease the sound and thermal energy you decrease the noise and friction acting on the door. |
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What does thermal conductivity mean? |
The rate at which heat passes through specific materials. |
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What affects the rate at which buildings cool? |
-The surface area of the building -The material used to make it |
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How can insulation reduce unwanted energy transfers? |
Insulation can reduce the transfer of thermal energy from the house walls or roof by |
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Describe how energy is transferred from the cooker to the water. |
When you heat up water the electrical energy in the cooker transfers into chemical energy and then thermal energy which transfers into the pan. The water particles in the pot vibrate and pass on the thermal energy to each other, which heats up the water. |
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Describe how the energy spreads out through the water of a pan being heated. |
Th heat is transferred by convection. The particles vibrate and pass on the thermal energy to each other which then transferred into kinetic energy as the water particles move. |
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Explain why bubble wrap is a good insulating material. |
The air inside the bubble wrap traps the thermal energy that is being protected by the bubble wrap. This means no air escapes though tty bubble wrap therefore keeping the object or substance warm. |
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Straw bale houses have very thick walls. Give two reasons why houses with cavity walls filled with straw are better than normal brick walls. |
Normal brick walls have no insulating material preventing the heat from escaping the house through conduction. However houses with cavity walls |
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Give two reasons why the cavity wall keeps the house warmer than a single wall. |
-Traps air in gap between two walls -The cavity wall is densely packed so that the heat particles can't escape as they get trapped within the wall. |
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Suggest why modern buildings have the cavity filled with foam or a similar material. |
Foam has lot of air gaps which contain any escaping thermal energy inside the house and stop it from conducting through the cavity walls. |
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What factors affect the GPE stored in an object? |
- The mass of the object- The strength of the gravity- How far the object has been moved upwards (use equation to calculate) |
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How do you calculate the GPE of an object? |
GPE (J) = Mass (kg) x GFS (n/kg) x change in vertical height (m) |
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How do you calculate the amount of kinetic energy stored in a moving object? |
KE (J) = 1/2 x Mass (kg) x speed2 (m/s2) |
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Explain why a car moving at 20m/s is storing more kinetic energy than a cyclist moving at 2 m/s. |
A car moving at 20m/s is storing chemical energy, electrical energy, thermal energy, kinetic energy. However the bike is only storing kinetic. |
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What non-renewable energy resources can we use? |
-Coal -Natural gas -Oil -Nuclear power |
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How are the different non-renewable resources used? |
They are used in most planes, vehicles and ships because they store a lot of energy and they are easy to store and use. Natural gas is burnt and used in some homes for heating and cooking. |
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How is the use of non-renewable energy resources changing? |
We are not using them as much because we are discovering different ways to power our machines with renewable resources. |
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Describe two reasons why fuels made from oil are used in vehicles. |
-They are easy to store -They store a lot of energy |
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Describe two advantages of using natural gas instead of coal to generate electricity. |
- They produce less carbon dioxide - The factories where they are used produce less carbon dioxide therefore they pollute the earth less whilst using the same amount of energy as renewable resources. |
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Give one advantage of nuclear power over fossil- fuelled power stations. |
Nuclear power stations don't emit any gases. |
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Give two disadvantages of nuclear power over fossil-fuelled power stations. |
The waste they produce is radioactive and they are very expensive to decommission. |
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What renewable energy resources can we use? |
-Tidal power -Solar power -Bio-fuels -Wind power -Hydroelectricity |
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How are the different renewable resources used? |
-Solar energy is used to convert solar energy to electrical energy and can be used to heat water for uses in homes. Not available all the time. |
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How is the use of renewable energy resources changing? |
Renewable energy resources are being used more to reduce negative environmental impacts such as global warming and high CO2 emission release. We now use it in our homes, cities and even now to power our vehicles. |
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What advantage do almost all renewable energy resources have over fossil fuels for generating electricity? |
-They do not run out -They (mostly) do not emit CO2 when used to generate electricity. (no fuel is burned) |
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State which renewable resources - are available all the time - are available at predictable times -can only be used in certain places -depend on the weather |
-All- Hydroelectricity (as long as dam doesn't dry up), Bio-fuels -Predictable- Tidal power, Wind turbines -Certain places- Tidal power -Depend on weather- Solar (day/night) |
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What is hydroelectricity? |
Hydroelectricity is generated by falling water in places where water can be trapped in high reservoirs. Hydroelectric power stations can be started and stopped v.quicky unlike fossil fuel power stations. |
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What are wind turbines and how do they generate electricity? |
Wind turbines generate as long as the wind speed is not too slow/fast. A lot of wind turbines are needed to produce the same amount of energy as a fossil-fuelled power station and some people think they spoil the landscape. |
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What is tidal power and how does it generate electricity? |
Tidal power is generated when a dam across a river estuary turn its turbines as the tide flow in and out. It is not available all the time as the tides are predicted. |
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What are bio-fuels and how do they generate electricity? |
Bio-fuels are made from animal and plant waste. They are carbon neutral because when they burn, they release the same amount of CO2 that they took form the atmosphere when the plant grew. |
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What is meant by the conservation of energy? |
Energy cannot be created or destroyed. It can only be transferred from one store to another. This is called the law of the conservation of energy. This means that the total energy transferred by a system is the same as the energy put into the system. |
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What does dissipate mean? |
Cause energy to be lost through its conversion to heat. |
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Remember! |
REMEMBER GRAVITATIONAL FIELD STRENGTH IS ALWAYS 10N/KG. |
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Explain how mechanical processes become wasteful when they cause a rise in temperature. |
Most machines waste energy when they get hot. Whenever two moving parts touch each other, friction causes them to heat up. The thermal energy stored in the hot machine is transferred to the surroundings by heating, which dissipates the energy. The energy is wasted energy. |
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Describe the movement of energy in a transverse wave |
The energy moves parallel to the direction of travel of the energy |
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Describe the movement of energy in a longitudinal wave |
The energy move perpendicular to the direction of the travel of energy |
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What is the frequency of a wave? |
The number of waves passing a point each second |
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What is the period of a wave? |
The length of time it takes one wave to pass a given point |
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What is the amplitude of a wave? |
The distance from a point on one wave to a point in the same position on the next wave |
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What is the velocity of a wave? |
The speed of the wave in the direction it is travelling |
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How do you work out the wave speed of a wave? |
wave speed (m/s) = frequency (Hz) x wavelength (m) |
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What does the medium a wave is travelling change? |
The speed of the wave |
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How can you measure the speed of a sound wave? |
-You can stand in front of a wall and measure the time takes for an echo of a loud sound to reach you -S = d / t |
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How can you measure the speed of a water wave? |
-Measure the time it takes for a wave to travel between two fixed points such as buoys -The speed can be calculated from the time and distances between the points |
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How can you measure the speed of waves in the lab? |
-Use a ripple tank with a strait dipper near one side of tank with a ruler fastened to one side -Count how many waves are formed in 10 seconds -Measure the different waves by varying the current -Use the wavelength and the frequency to work out the speed -Or measure the distance the waves travelled and use that to calculate the speed that way |
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What is refraction? |
The change in the direction of a wave that happens at the interface when the wave is traveling through two different mediums |
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What is the line called at right angles to the interface? |
The normal line |
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What direction does the wave change to when it is travelling from air to glass / water? |
Light refracts towards the normal |
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What direction does the wave change to when it is travelling from glass / water to air? |
Light refract away from the normal |
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Which does light travel fastest in? -Air -Glass -Water |
Light travels faster in air than in water and glass |
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What causes the change in direction of light to change? |
The change in speed because of the density of the medium it is traveling through |
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Does light bend towards or away from the normal line when it slows down? |
The light bends towards the normal line |
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What affects the speed of waves? |
How deep the water is |
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What is an electromagnetic wave? |
Waves which can travel through the vacuum of outer space |
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What do lower frequencies of visible light appear as? |
More blue |
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What do higher frequencies of visible light appear as? |
More red |
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All electromagnetic waves are .............. |
Transverse |
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What do hot objects emit? |
Infrared light -The hotter the object the more light it emits |
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What is an interface? |
Where electromagnetic waves pass a boundary, and move at different speeds, between two different materials |
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What is the change of direction of waves called? |
REFRACTION |
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What is the light ray approaching the interface? |
Incident ray -Angle of incidence |
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What is the angle between the normal and the light ray leaving the interface? |
Angle of Refraction |
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What are the colours of visible light? |
red,orange,yellow,green,blue,indigo and violet ROY G BIV |
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What is the shortest wavelength? |
Gamma rays |
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What is the longest wavelength? |
Radio waves |
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Which has the highest frequency the longest or shortest wavelength? |
Shortest wavelength |
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Which has the lowest frequency the longest or shortest wavelength? |
Longest wavelength |
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List the electromagnetic spectrum in order of lowest frequency to highest frequency |
-Radio waves -Microwaves -Infrared -Visible light -Ultra violet -X-rays -Gamma rays |
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What can infrared be used for? |
-Communication at short ranges -Remotes, computers -Grill or toaster transfers energy to food -Security systems |
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What can microwaves be used for? |
-Communications and satellite transmissions -Mobile phones -Microwaves |
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What can radio waves be used for? |
-Transmitting radio broadcasts and tv programmes -Other communications via satellites |
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What are radio waves produced by? |
Oscillations in electrical currents |
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What is the ionosphere used for? |
A layer in the atmosphere that can refract some frequencies of radio waves to send them back to Earth |
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What kind of waves pass through the ionosphere? |
Microwaves |
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What is the ionosphere? |
A region of charged particles in the atmosphere |
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What can ultraviolet be used for? |
-To disinfect water by killing microorganisms in it -Security markings |
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What can x-rays be used for? |
-They can pass though fat but not bone -Bone absorbs the rays -Used in medicine -Examine the insides metal objects and luggage |
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What can gamma rays be used for? |
-Sterilise food and surgical instruments -Kill cancerous cells in radiotherapy |
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How do gamma rays kill cancerous cells? |
-A chemical that emits gamma rays is injected into the blood and collects inside cancerous cells -A scanner then locates it |
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What are the dangers of infrared waves? |
-Damage or destroy cells -Cause burns to the skin |
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What are the dangers of ultra violet waves? |
-Cause sunburn -Damage DNA -Skin cancer -Damage our eyes |
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What are the dangers of x-rays and gamma rays waves? |
-Can cause mutations in DNA -Cause cancer |
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What can radiation do to atoms? |
Cause atoms to lose electrons and become ions |
