1.ENERGY


Is the capacity of a body to perform transformation and do work.Food labels provide us information abaut the nutrional qualities of the food we eat.Our bodies are like machines that transform the energy in food into metabolic (chamical) energy and muscular (mechanical) energy.
Muscular energy was the only source of energy that people had.
Technological objects that we use also require energy to function correctly and perform tasks.


1.1 FORMS OF ENERGY:

• Potential:Associated with the heigh of an object above the ground,or the storage of energy in a spring.
• Kinetic:The energy of physical movement.
• Mechanical:The sum of potential and kinetic energy.
• Sound:The energy of sound waves,which are produced by vibrations and propagated though a physical médium.
• Electrical:The product of an electrical current.
• Nuclear:The energy in the nucleus of an atom.
• Luminous:Associated with light.
• Thermal or Calorific:Associated with the movement of particles in matter.
• Chemical:Results from the formation or descomposition of substances.
• Electromagnetic:Occurs when electrical currents créate magnetic fields.

1.2 UNITS OF MEASUREMENT FOR ENERGY:


Energy is measured in "joules".When energy takes the form of heat,we often express it as "calories".

1.3 POWER:

Power is a measurement of how quickly work is done.The power of a machine is the amount of work that it can do in a certain amount of time.

TEMA 6: ENERGY

• Answer:

      1.What is the difference between a form of energy and an energy source?

• Which an energy source is a natural resources that we can use to generate differents forms of energy and form of energy is present in all physical phenomenon.

      2.Can you name an energy source?

• Gas,petroleo,sun...

      3. What is a renewable energy source?

• Renewable energy sources come from natural resources.That we cannot use up completely.

      4.Where do oil,gas and coal come from?

• From natural resources

      5.What types of power stations do you know?

• Thermosolar power,nuclear power and hydroelectric power,marine and wind power.

      6.How is electricity transported from a power station to your home?

• First raising the voltaje,second high voltaje lines,third reducing the voltaje and as this point,the power is distributed.

      7.What do the terms greenhouse effect and acid rain mean? How ae they related to energy production?

• "G.E": Which acreces the courths aaverage temperature.
• "A.R": Contributes to the acification of our oceans.

      8.What others points could you add to your poster or leaflet?

• Eviromental consequences.

5.1 DIRECTION CONTROL:RATCHETS:
A rached is a mechanism that controls the direction of motion.Some ratchets are reversible,so they can turn and lock in one direction or another.

5.2 SPEED REDUCTION:BRAKES:
Brakes use friction to reduce speed.They are activated by certain levers.The lever transmits forcé to an output receptor,which puts pressure on the Wheel.There are various types of brake systems according to where the friction is produced:

• Disc brakes:A disc is connected to an axle.Brake pads apply pressure to the disc.
• Band brakes:A drum is connected to an Axle.A flexible band applies pressure to the outside of the drum.These brakes were used in carriages and they depended on the strength of the driver.
• Drum brakes:A drum is connected to the axle.A pair of brake shoes apply pressure to the inside of the drum.
   
  
  

Cam mechanisms:A cam is an irregularly shaped device that rotates on a shaft.When the cam rotates,it pushes a special bar called a follower.The follower can move other parts or it can turn a switch on and off.Some cams are circular,but with an axis of rotation that is off-centre.These are called eccentric cams because they rotate in an irregular or eccentric way.

Crankshaft mechanism:We can multiple rods to one shaft.The rods are connected to cranks,and the cranks are connected to the crankshaft.A crankshaft mechanism can synchronise the movements of various parts,such as the multiple pistons of a car engine.

4.2 RECIPROCATING ROTARY-LINEAR TRANSFORMATION:
The pistons of a car engine produce into continuous rotary motion.Some mechanism work in the opposite way,transforming rotary motion into reciprocating linear motion.

Crank and rod mechanism:The piston moves a rod forwards and backwards.This rod turns the first Wheel.The second Wheel turns becouse it is connected to the first Wheel by another rod.

4.1 ROTARY-LINEAR TRANSFORMATION WHEEL:
they let us move more easily because they reduce our contact with the ground and decrease friction. However,if there isn't enoungh friction, the wheels can slide out of control.
With each rotation, a Wheel moves forward a distance that is equal to its circumference.As a result,we need less force to move vehicles with larger wheels and they move more quickly.

Rack and pinion mechanism:The rack is a bar with many teeth and the pinion is a gear with teeth that interlock with the rack. When the pinion rotates,the rack moves in a linear direction.

Nut and bolt mechanism:A bolt or shaft with a spiral Groove and a nut that turns around it.We can turn and lighten the nut in order to hold things together.We can a use a nut and bolt mechanism to lift loads because it fuctions as a reducing system.

Winch and crank mechanism:A winch is a cylinder that rotates around a horizontal axis.Then we turn the crank to rotate the winch.The rope rolls up around the winch and lifts the load.The crank increases the force and the winch transform rotary motion into linear motion.The increase in force is proporcional to the ratio between the radius of the crank and the radius of the winch.

F*d=R*r