When we use petrol we are ultimately using stored energy from the sun. Plants capture the energy when growing, and then through a long process of decay and compression this plant matter is converted into a fossil fuel. An interesting question is how much sunlight is needed to produce a quantity of petrol. To estimate this, let's assume the petrol has come from wood, and let's assume we have a fast-growing wood source such as Pinus radiata. Assume also: a mature tree contains around 3 m3 of timber; a tree is harvested when 35 years old; the density of wood is around 500 kg/m3; 2 kg of wood makes 1L of petrol; a tree receives on average 8 hours of sunlight per day. How many "hours of sunlight" are stored in 1L of petrol? i.e. how many hours of sunlight does a tree need to be exposed to, to produce the amount of wood needed to make 1 L of petrol? Give your answer to two significant figures.
Nuclear Fission
Nuclear fission is a type of nuclear reaction in which heavier nuclei split into lighter nuclei by releasing a large quantity of energy. The elements like uranium-235 and plutonium-239 isotope undergo nuclear fission releasing energy. When nuclei undergo fission, some quantity of mass is lost. The lost mass is converted to nuclear energy. Nuclear fission reaction is used in nuclear power plants and atomic bombs. In nuclear power plants, nuclear reactors are used to generate electricity.
Endothermic Nuclear Reaction
A nuclear reaction can be described as a process where two atoms, or two nuclei or nucleus and subatomic particles such as a proton, neutron interact together, and a large amount of energy is produced and new elements are also produced.
When we use petrol we are ultimately using stored energy from the sun. Plants capture the energy when growing, and then through a long process of decay and compression this plant matter is converted into a fossil fuel.
An interesting question is how much sunlight is needed to produce a quantity of petrol. To estimate this, let's assume the petrol has come from wood, and let's assume we have a fast-growing wood source such as Pinus radiata. Assume also:
- a mature tree contains around 3 m3 of timber;
- a tree is harvested when 35 years old;
- the density of wood is around 500 kg/m3;
- 2 kg of wood makes 1L of petrol;
- a tree receives on average 8 hours of sunlight per day.
How many "hours of sunlight" are stored in 1L of petrol? i.e. how many hours of sunlight does a tree need to be exposed to, to produce the amount of wood needed to make 1 L of petrol? Give your answer to two significant figures.

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