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energy
something that is need to make things happen. Energy is the ablitiy to do work
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Basic yet important energy points (5)
- Energy cannot be created to destroyed
- All living things have and need energy
- energy existis in different forms
- energy canchange forms
- Energy is not a substancew it does not take up space and cannot be weighed
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Measuring energy
Energy is measured in joules. Joules is a very small unit so kilo joules are offen used. the symbol is J or kJ
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Two main forms of energy
Potential energy (stored energy) and active energy
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Potential energy types
- Gravitational
- elastic
- nuclear
- chemical
- magnetic
- (GENCM)
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Active energy types
- Sound
- heat
- radiant (light)
- eletrical
- kinetic
- (SHERK)
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Law of conservational energy
Energy cannot be created or destroyed it only changes from on form to another. The total out put remains constant as the input
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Weight
Force pf gravity pullling towards the earth. It is gravity times mass
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Measuring forces
Force is measued in newetons
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Four types of forces
Lift, gravity, thrust, and friction
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Un/balenced forces
- when forces sre balence the object is stationary or traveling at a constanst speed
- When forces are unbalenced the oject is acclerating or decelerating
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Net force
When net force is 0 the forces are balenced. When net force isn't 0 the forces are unbalenced
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Calculating net force/resulant force
- If forces are acting in the same direction you add them together
- If the forces are acting in the opposite then we subtract the the bigger value from the smaller
- the object will move in the direction of the bigger force
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Distance time graphs
- Distance on y-axis, time on x-axis
- Constant upwards slope means travelling at a constant speed
- Straight line means stationary
- curving upward means accerating
- curving downwards means decellerating
- downwards slope means returning to start
- slope is speed, rise over run
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Speed time graph
- speed y-axis, time on x-axis
- upwards slope - accerating
- downwards slope - declerating
- horizontal on base - stoped
- horizontal in air- constant speed
- total distance is area under the line
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Accleration due to gravity
when an object falls verically it accerates due to gravity. This accerationna of a free falling object is called acceration due to gravity. This acceration due to gravity has a value of 9.8ms-2 but in calculations it is rounded to 10ms-2
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Terminal Velocity
when objects fall from a large height, the do not continually accerate but eventually moves at a constant speed. This is beacuse air resistance increases as speed and balences out the down wards force of gravity, and the object cannot acclerate
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Discus how the speed of a car effects the damage in a crash
Kinetic energy is proportional to the square of speed when speed is doubled the kinetic energy is quadrupled by factor 4. Therefore the impact is heavier and tyhe more damage
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