3. Work
• When a force (Newton, N) moves an object
work is done.
• Work is a measure of the amount of energy
(Joules, J) used in moving the object.
work done = force applied x distance moved
W = F x d
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7. • Thrust – a forward push
• Upthrust – the upwards force on a body in a
liquid or a gas
8.
9. Power
• Power (Watts, W) is the rate that work is done
– how fast energy is used.
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10. Kinetic Energy
• The energy of motion.
• All moving things have kinetic energy.
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11. Calculating kinetic energy
Ek = ½mv2
m = mass of object (kg)
v = the objects speed (m/s)
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12. Potential Energy
• An object can store energy – this is dependent
on position.
• Includes - gravitational, chemical and elastic
energy.
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22. Gravitational Potential Energy
Ep = mgh
m = mass (kg)
g = acceleration due to gravity (9.8 m/s2)
h = height (m)
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23. Law of Conservation of Energy
• States that energy cannot be created or
destroyed, just transformed from one form to
another.
– Therefore, energy never
‘disappears’.
– Energy that is transferred to
unwanted forms is wasted energy.
25. Energy Conversion Efficiency
• Some energy can be ‘lost’ as heat and sound.
• Energy is lost in the form of heat and sound
each time the rollercoaster moves. If this did
not occur the rollercoaster would keep on
moving forever.