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14 Cards in this Set
- Front
- Back
Speed
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Average speed is calculated in m/s using TOTAL DISTANCE/TIME
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Velocity
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•Velocity is an objects speed in a give direction
•A change in velocity is called acceleration •Change in velocity= Change - Original Velocity |
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Acceleration
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acceleration= change in velocity/time taken
Acceleration= force (n) / mass (g) A negative acceleration (deceleration) means that the object slows down |
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Resultant Force
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•The single force that would make an object move in exactly the same way as all the original forces acting together
• If there is no resultant force, forces are balanced. It remains stationary. • If there is a resultant force, the object accelerates in the direction of the unbalanced force |
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Energy transfer and Waste
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• The Law of Conservation of Energy States that energy cannot be created or destroyed when it is transferred. All energy is usefully transferred, dissipated, or stored
• Energy=Power x Time |
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Efficiency
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Efficiency = Useful Energy / Total energy in
The answer is always a decimal less than 1 |
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Refraction
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•Waves can be refracted (change direction)
• They change speed in different materials. |
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Reflection
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•Waves can be reflected
• The angle reflected is the same as the angle between an incoming Ray and the normal |
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Diffraction
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• Waves can be diffracted (Spread out through a gap or round an obstacle)
• Diffraction is greatest when the wavelength is about the same size as the gap or obstacle. |
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Electromagnetic Spectrum
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• Electromagnetic radiation is a continuous spectrum of transverse waves carrying energy
• Velocity can be calculated with; Speed=frequency x wavelength • The shorter the wavelength of an electromagnetic wave, the higher the frequency • Electromagnetic waves with a short wave length & high frequency carry most energy |
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The National Grid
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• Power (watts) = Voltage (v) x Current (amp)
• Step up transformers- increase the voltage to 400,000V • Increasing voltage in power cables reduces the current. Wires heat up less, so thinner cables are needed and less energy is wasted • Step down transformers in substations reduce reduce the voltage. Electricity is supplied at 230 V in homes |
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Sound
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• Vibrating objects creates sound waves are longitudes mechanical waves and cannot pass through a vacuum
• All sounds can reflected, refracted or diffracted • Loud sound waves have a large amplitudes; quiet sound waves have a small amplitude • High pitched notes have a short wavelength and high frequency; low pitched sounds have a long wavelength and low frequency. High frequencies carry more energy |
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Ohms Law
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• For some materials, voltage is proportional to current, and resistance is constant
• A voltage-current graph can be used to find the current in wire at a certain voltage. These values are used to calculate resistance. |
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Resistance
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• Resistance is calculated using;
Resistance= voltage / current |