IGCSE Coordinated Science: Energy

IGCSE Coordinated Science: Energy Energy 1. Know that energy and work are measured in joules (J), and power in watts (W). The energy of an object is measured in Joules (J) . 1000 Joules = 1kilojoule (kJ) The power of an object is measured in Watts (W). 1000 Watts=1kilo Watt (kW) 2. Demonstrate understanding that an object may have energy due to its motion (kinetic) or its position (potential), and that energy may be transferred and stored. All objects have what we call, internal energy in its molecules. Internal energy is made out of Kinetic Energy (due to the motion of the molecules), and Potential Energy (due to the position of the object). You can’t create or destroy energy, energy is conserved. However, energy can be transferred and stored. For example, when you jump of a cliff (god forbid), the Potential Energy will slowly be converted to Kinetic Energy. The NET Energy remains the same, but you see a transfer of energy from one form to another. 3. Recall and use the expressions: K.E. = ½ mv2 and P.E. = mgh Kinetic Energy (J) = 1/2 x Mass x Velocity Squared Potential Energy (J) = Mass x Gravitational Force x Height 4. Give and identify examples of energy in different forms, including kinetic, gravitational, chemical, strain, nuclear, thermal (heat), electrical, light and sound. Kinetic Energy I guess anything that is in motion has some sort of kinetic energy. Examples include: ● Running a marathon ● A ball falling off the cliff. Gravitational Potential Energy. This is the energy that exists due to the position of the object.

A good example is: ● A man standing on a cliff will have gravitational potential energy. Chemical Energy This is the potential energy present in a substance that allows it to engage in chemical reactions. A good example is: ● Chemical Energy in a battery. Strain Energy Strain energy is released when the constituent atoms are allowed to rearrange themselves in a chemical reaction or a change of chemical conformation in a way that: A good example is: ● Energy in an elastic band. Nuclear Energy ● Nuclear bombs (unsurprisingly), have nuclear energy. Thermal Energy ● Sweating after a run ● Heat released after cooking some rice. Electrical Energy ● Turning on your TV requires electrical energy. Sound ● Sound from microphones can be passed off as sound energy. Light ● Turning on a lightbulb. 5. Give and identify examples of the conversion of energy from one form to another, and of its transfer from one place to another. ● In a battery, chemical energy changes into electrical energy.

● In a wind turbine, wind is transformed into mechanical energy . Then attached to a transformer where energy is then transformed into electrical energy. ● Nuclear energy is transferred into heat and electrical energy in a nuclear plant. ● When a ball falls off a cliff, gravitational potential energy is being transferred into kinetic energy. 6. Apply the principle of energy conservation to simple examples We discussed this briefly just now. The Principle of energy conservation states that “energy can neither be created nor destroyed”. A really good example can be seen when we throw a ball of a cliff. When the ball is at the top of the cliff, its Gravitational Potential Energy is at its highest, as GPE = mgh and “h” is at its maximum at the top of the cliff. However, when you throw the ball off the cliff, you may think that as “height” is decreasing, the GPE of the ball is also decreasing. As a result, the total energy of the ball must be decreasing as well right? Wrong. As the ball falls, the energy it loses as Gravitational Potential Energy is being transferred intoanother form of energy, kinetic energy, and the amount transferred is the exact same as the amount lost via Gravitational Potential Energy.