SELF ASSESSMENT 15.6

 1. FOSSIL FUEL ARE CONSIDERED AS A SOURCE OF ENERGY WHICH IS NOT RENEWABLE. WHY IS IT SO?

Fossil fuels are considered non-renewable sources of energy because when they are burnt, they are finished. When the last barrel of oil has been pumped out of the ground there is no more. And also it's non-renewable because fossil fuels take hundreds of millions of years to form under the Earth's surface. It will take another million years for more to be produced, so we only have a limited supply. 

2. WHAT HAPPENS IF THE FUEL CONSUMPTION IS NOT SPREAD?

If fuel consumption is not spread, its going to be harder for us to live. Since fossil fuels are used to power thing up for example oil is use for cars, coal for industries, natural gas for stove, and many others. So thats why if fuel consumption is not spread is going to be harder for us to live. And because of that we have to use alternative energy like solar and wind energy.

3. WRITE DOWN THE DANGEROUS ISSUES OF HAVING A NUCLEAR POWER PLANT.

Although nuclear power plants offer an new source of energy, nuclear power plants could also be dangerous as it is radioactive. For example in Japan when there was tsunami. The tsunami hits the nuclear power plant. Because of that people who lives nearby have to move since of the water that is contaminated by the nuclear power plant.

4. ACCORDING TO YOUR OPINION, IN ORDER TO PRODUCE ELECTRICAL ENERGY, WHAT IS THE BEST ENERGY THAT FITS WITH THE CURRENT SITUATION AND IS POLLUTION FREE?

The best way to produce electricity and its pollution free is Wind Energy or Solar Energy. Both wind and solar energy are pollution free because wind energy produces energy from wind that is received using a windmill that spins while solar energy uses solar panels to get energy directly from the sun. By using these alternative ways to get energy easily, there are also some advantages of using these alternative energy. for example wind energy; it needs lots of wind speed and it  generate a little energy. While solar energy; its low efficiency. it requires large areas of land.    

5. WRITE DOWN YOUR SUGGESTIONS IN ORDER TO PRODUCE A VERY HIGH TEMPERATURE, SO THAT A LARGE AMOUNT OF ELECTRICITY CAN BE GENERATED FROM THE USE OF SEA WATER.

By using nuclear energy. Since nuclear energy is caused by the splitting of the atomic nucleus, the  reaction is called fission. Fission is the splitting of a heavy nucleus into two lighter nuclei that releases a huge amount of energy and fusion is the process of joining the nuclei of atoms accompanied by huge energy release. The fuel for fusion is deuterium or heavy hydrogen which you can get from sea water. Sea water contains unlimited amounts of hydrogen. But we need at least 100 million degrees Celsius to join the nuclei of atoms which requires advanced technology.

     SOURCES OF ENERGY

• Non-Renewable Energy

A source of energy which is not renewable is the source of energy which cannot be regenerated when it is used. Examples of non-renewable energy is fossil fuel. Fossil fuel are also called conventional fuel.

• Renewable Energy

Source of energy which is renewable is the source of energy which can be regenerated when it is used up. Nowadays, renewable energy is used as an alternative energy to replace conventional energy and fossil fuels. the sources of alternative energy are, for example, wind energy, waterfall energy, solar energy, nuclear energy, tidal energy, geothermal energy, and biomass energy.

WIND ENERGY:

Wind energy is one of many renewable sources of energy, because it always available in nature. back then, windmills are used to grind and to pump water. Nowadays, windmills are used to drive electric generators to produce electricity.

WATERFALL ENERGY:

Moving water can rotate turbine which further produces electricity. There are Potential and Kinetic energy acting upon it to generate electricity in a hydroelectric power plant. An artificial waterfall can be built by constructing a dam. A dam can help to generate electricity in hydroelectric power plant.

SOLAR ENERGY

Solar energy is easy to get and pollution-free. there are two methods of collecting solar energy; they are a passive and an active method.

•  PASSIVE METHOD:

 Passive method has been used since a long time by the Romans to heat up their bathing water. Nowadays, glass windows are placed in buildings to get the warmth from solar energy.

• Active Method:

The active method, uses solar panels to collect and store solar energy. the solar energy panels transforms solar energy into thermal energy. Solar panels are made up of black plates covered by transparent glass or plastics.

NUCLEAR ENERGY

Hiroshima and Nagasaki were destroyed by an atomic bomb. that huge source of energy came from energy release generated by the splitting of the atomic nucleus. The reaction is called Fission. This fission produces a huge amount of energy called nuclear energy. Nowadays, nuclear energy is used for electric power plant, and usually called a nuclear power plant.

FISSION:

The operation of a nuclear power plant is based on fission. Fission is the splitting process of a heavy nucleus into two little nuclei.

WORK QUESTIONS

1. A tugboat pulls a ship with a constant force of 5000 N, causing the ship to move through a harbor. How much work does the tugboat do on the ship if each moves a distance of 3 km?

            
           Answer:     3km = 3000 m   
                               
                              W = F x D
                              W = 5000 x 3000
                              W = 15,000,000

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  2.  A husky dog does 20 kJ of work as he pulls a sleigh with a force of Through what distance does he pull it?

           

Answer:     20kJ = 2000 J

                                  W = F x D

                           2000 J = 340 x D

                                   D = 2000 J / 340 

                                   D =  58.85

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       3.  What is the weight of a mass of 100 kg? Find the work done in raising a mass of 100 kg through a vertical height of 60 m.

         Answer:   mass = 100 kg

          Force Gravity = Mass x Gravity

                         =  100 x 10

                                 =   1000 N

 W: F x D        

 W: 1000N x 60m         

W: 1000N x 60m

  W: 60000J

  W: 60kJ

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        4.   Carlos does a chin-up in gym class and raises himself 0.8 m. If Carlos has a mass of 62 kg, how much work does he accomplish?

        Answer:   Mass = 62 kg

  Force Gravity = Mass x Gravity

                         =  62 x 10

                                 =   620 N

  W: F x D

     W: 620N x 0.8m

     W: 496J

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    5.  A girl pushes her little brother on his sled with a force of 300 N for 750. m. How much work is this if the force of friction acting on the sled is 

(a) 200 N

(b) 300 N?

Answer:   

(a).                                      

W: F x D
W: (300-200)N x D
W: 100N x 750m
W: 75000J
W: 75kJ

(b). 

W: F x D
W: (300-300)N x D
W: 0N x 750m
W: 0J

her little brother wont move

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Energy

           Everything that performs work is said to have energy. Since work and energy have a direct relationship, so energy is measured in the same unit , that Joules (J) or calories (cal).

1 J = 0.24 calories (cal)

1 calorie = 4.2 J

1 kcal = 4,200 J, to be exact 1 Kcal = 4,180 Joules

*Energy is the ability to perform work*

The followings are some forms of energy: Sound Energy, Spring Energy, Chemical Energy, Light Energy, Electrical Energy, Nuclear Energy, Mechanical Energy, Kinetic Energy, Potential Energy

                                     

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WHAT IS POTENTIAL AND KINETIC ENERGY

(FORMULA)

Potential Energy is the energy possessed by an object because of its relative position.

               

  Formula: Potential Energy = Mass x Gravity x Height

                                   

                                         PE = M x G x H

Kinetic Energy is the energy possessed by an object because of its motion.

           

            Formula: Kinetic Energy = 1/2 x Mass x V^2

                      

                                         KE =   1/2 x M x V^2

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EXAMPLES OF POTENTIAL AND KINETIC ENERGY:

1.  A coconut with a 2 kg mass is hanging at 6m high. If gravitational acceleration g = 10 m/s, determine the potential energy of the coconut relative to the ground.

Solution:    

                   Given:  m = 2kg 

                                h  = 6m

                                g  = 10 m/s

PE = M x G x H 

     =  2 kg x 10 m/s x 6 m = 120 kg m/s

     =   120 Joules

2. An athlete is practicing himself by running with a 5 m/s speed. if he has a 40 kg mass, what is his kinetic energy?

        Solution:

     v = 5 m/s 

    m = 40 m/s

   KE = 1/2 mv^2

= 1/2 x 40 kg x ( 5 m/s ) ^2 = 20 kg x 25 m/s 

=  500 Joules

                                            

3.  A 5 kg mass object is 8 m from the ground. If the gravitational acceleration is 10 m/s, the potential energy possessed by the object is?

Solution:  

m = 5 kg

g = 10 m/s

h= 8 m

PE = M x G x H

PE=  5 kg x 10 m/s x 8 m

PE= 400 Joules