Energy transferred when moving a force of 1 newton a distance of 1 metre in the direction of the force
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How do we calculate work done?
Force (N) * Distance (m)
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What is work done measured in?
Joules
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How do we work out kinetic energy?
1/2 * m * v squared
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How do we work out mass?
2Ek / v squared
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How do we work out velocity?
square root of 2Ek/ m
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What is the principle of conservation of energy?
Energy cannot be created or destroyed, only transferred
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Work done is equal to......
Kinetic energy
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How do you convert from km/h to m/s?
*1000/3600
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How do you convert from km/min to m/?
*1000/60
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How do you convert from m/min to m/s?
/60
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How do you convert from km/s to m/s?
* 1000
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Where is GPE stored?
In things high up, above the Earth's surface
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How do we calculate GPE?
mass * gravity/acceleration/freefall * height
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How do we convert from joules to kilojoules?
/1000
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Why will a diver's kinetic energy as she hits the water be different to the GPE she gained climbing the diving board?
When she falls through the air she will have to do work against air resistance, energy is passed to the surroundings as heat/sound
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Why is a bus more likely to cause harm to a person than a van?
The mass of the bus is larger so it has a greater KE
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What is kinetic energy proportional to?
Velocity squared
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What happens to the kinetic energy when the velocity squared doubles?
It will quadruple
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What is momentum?
The quantity of motion of a moving body, vector
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How do we calculate momentum?
Mass * velocity
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What is the principle of conservation of momentum?
The sum of the momentum before a collision is equal to the sum of momentum after a collision as long as there are no external forces acting
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What three different types of collisions are there?
Elastic, inelastic and explosion
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What is an elastic collision?
A collision where the objects do not stick together, momentum conserved unless external forces are acting, total energy and KE conserved
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What is the formula for an elastic collision?
MaUa + MbUb = MaVa + MbVb
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When two objects push each other apart, what do they move with?
Different speeds if they have unequal masses, equal and opposite momentum so their total momentum is zero
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What is an inelastic collision?
A collision where the objects stick together, momentum is conserved unless external forces acting, KE not conserved but dissipate as thermal/sound
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What is the formula for an inelastic collision?
MaUa + MbUb = (Ma + Mb) V
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What is an explosion?
A collision where the objects move off in opposite directions, momentum before collision is always zero, momentum is conserved
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What is the formula for an explosion?
0 = MaVa + MbVb
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How do we work out the force?
Change in momentum / time
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What do you write for momentum questions concerning safety?
Increases impact time, decreases rate of change in momentum/ acceleration, reduces the force
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How do you use the idea of momentum to explain occurences?
Momentum is conserved, object is stationary, equal and opposite momentum, zero momentum before and after the jump, object has to go in opposite direction to other object
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Other cards in this set
Card 2
Front
What is work done?
Back
Energy transferred when moving a force of 1 newton a distance of 1 metre in the direction of the force
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