Forms of Energy
Energy Transfers and Conversions
Conservation of Energy
Energy Calculations
Energy Resources
100
Give 3 sources of chemical energy.
- Fuels (petrol, natural gas, coal, wood) - Food - Muscles - Batteries
100
What is the other word for energy conversion?
energy transformation
100
Which form of energy is wasted the most?
Thermal (heat) energy.
100
What is the formula for calculating efficiency?
Efficiency = (Useful Energy Output/Energy Input) x 100%
100
Explain how wind power relies on energy from the sun.
The sun heats some parts of the earth more than others. The heated air expands and starts to move around which is how the wind is started.
200
List 9 forms of energy.
- Kinetic energy - Chemical energy - Light energy - Sound energy - Internal energy - Nuclear energy - Electrical energy - Strain energy - Gravitational potential energy - Thermal (heat) energy
200
Which forms of energy does chemical energy in the muscles of a bird transform into ?
Kinetic energy, gravitational potential energy, thermal energy.
200
What is the second form of energy most commonly wasted?
Sound energy.
200
What is the G.P.E of a ball mass of 5kg when it is held up 4m above the floor.
G.P.E = mg*h = 5 * 10* 4 = 200J
200
What would be very useful in an area that is very hot, but has no electricity?
Solar cells.(photocells)
300
What is the difference between thermal (heat) energy and internal energy?
Thermal energy is energy travelling from a hotter object to a cooler object. Internal energy is the energy stored in a hot object.
300
Give the equation of conversion in an accelerating car.
Chemical energy -> kinetic energy + thermal energy + sound energy
300
List 3 reasons why it is important to make good use of energy resources.
- Energy is expensive. - Supplies are often limited. - Use of energy can damage the environment.
300
Describe what happens to the G.P.E and K.E when a ball is falling down.
The G.P.E decreases and the K.E increases
300
List the factors that should be considered when comparing different energy sources.
Cost Reliability Scale Environmental impact
400
Why does nuclear energy produce more energy compared to other sources?
Nuclear energy produces more energy because its bonds are harder to break. Breaking bonds between sub-atomic particles releases a lot more energy because the bonds are stronger.
400
What is the principle of conservation of energy?
In any energy conversion, the total amount of energy before and after the conversion is constant.
400
What are the two main ways that heat energy is wasted? Explain.
- Thermal energy is produced when fuels are burned, but they readily lose energy to their surroundings even if they are well insulated. - Friction is created in moving objects. Although lubrication can help reduce friction, it is impossible to eliminate friction entirely. Friction generates heat.
400
The G.P.E of ball A of mass p which is held h meters above the ground, 10J. Ball B of mass 2p is held up 2h above the ground. What is the G.P.E of ball B?
G.P.E of ball A= mg*h = 10J = p*10*h = 10ph G.P.E of ball B= mg*h = 2p*10*2h = 40ph = 10ph* 4 = 10J * 4 = 40 J
500
Give 4 examples of energy stores and 4 examples of energy transfers.
Energy stores: - Kinetic energy - Gravitational potential energy - Chemical energy - Nuclear energy - Strain energy - Internal energy Energy transfers: - Electrical energy - Thermal (heat) energy - Light energy - Sound energy
500
Give the equation of energy conversion in a clockwork radio.
elastic energy -> kinetic energy ->electrical energy + thermal energy -> sound energy + thermal energy. the wound up spring of the clockwork mechanism is a store of elastic energy. When the spring rewinds, it turns a generator.(elastic ->kinetic energy) Then it becomes electrical energy which is later converted to sound energy. Heat energy is wasted in this process.
500
What is the definition of efficiency?
The efficiency of an energy conversion is the fraction of the energy that ends up in the desired form.
500
A wooden block of mass 10kg moved 5m when someone pushed it by 25N. What is the velocity of this block?
work done = force * distance moved = 25N * 5m = 125 J amount of work done = kinetic energy of the wooden block = 125 J K.E = 1/2 * mass * velocity^2 = 1/2 * 10kg * velocity^2 = 125 J velocity^2 = 5* 125 = 25 = 5*5 so velocity = 5m/s
500
explain how nuclear fusion works.
two energetic hydrogen atoms collide and fuse to form an atom of helium.
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