 Derive and use the equation for gravitational potential energy close to the Earth’s surface.  Use the equation for kinetic energy.  Solve problems involving exchange between kinetic and gravitational potential energy.  Apply the principle of conservation of energy to determine the speed of an object falling.

You should make sure you learn the definitions and understand what they mean. There are many different forms of energy and you should be able to name a few without too much trouble for example…. Energy Kinetic Sound Light Thermal Gravitational Chemical Strain/Elastic Nuclear Electrical

However what is energy? Energy is the ability to do work Whenever energy is changed from one form to another work is said to be done. For example a car converts chemical energy in the fuel air mixture into movement energy of the car. Energy in food allows you to run, skip, hop and jump merrily around. The strain energy stored in a long bow allowed the English archers to fire arrows at the French from great distances at the battle of Agincourt.

There are some we are not so interested in but it is worth your while knowing what they involve. Strain/Elastic Energy Due to the deformation of the bonds between atoms in the object. electrostatic forces Really the distortion causes work to be done against electrostatic forces. Energy is stored in the stretched bonds hence it is normally termed Elastic Energy. Nuclear Energy strong and weak forces Due to the strong and weak forces between the particles in the nucleus of a substance. Light Energy Due to the electromagnetic field disturbances that transfer energy from one place to another.

Chemical Energy Electromagnetic potential Due to the making and breaking of bonds between atoms in substances. Electromagnetic potential due to the arrangement of charges determines this form of energy. The bonds have energy stored in them and when bonds are made energy is given out but energy is needed in order to break them! Why do we need a match to start a fire?? Sound Energy Kinetic energy electrostatic forces Due to the Kinetic energy of the particles in the material transferring the sound. They rely on electrostatic forces to make each particles move Thermal Energy Due to the internal energy of a material which is linked to the Kinetic Energy of the atoms in it. The hotter a substance the more Kinetic Energy they have.

Gravitational Potential Energy The energy a body has by virtue of it’s position. The amount of energy depends on the mass, gravitational field strength and the height change from the initial position. Kinetic Energy The energy a body has by virtue of it’s motion. The amount of energy depends on the mass and velocity of the object. The two types of energy we need to be able to calculate are…… Felix Baumgartner's supersonic freefall

Potential Energy can refer to any form of energy that is a store such as Chemical Potential Energy, Gravitational Potential Energy, Elastic Potential Energy. It means the energy is stored and waiting to be released just like an object on a shelf, once caused to move off the shelf it can change the Potential energy → Kinetic energy. If an object is lifted you lose energy by doing work in your muscles and turn it into Gravitational Potential Energy as you do work against the pull of Gravity. It is referred to as Gravitational Potential Energy since the forces you are working against are Gravitational.

Gravitational Potential Energy When lifting an object work has to be done against the force of Gravity. Weight = mg The force is called the Weight = mg As we already know Work done = Force * distance moved Work done = Force * distance moved (in direction of the force - vertically.) Therefore… … … Gravitational Potential Energy = mg  h TESCO Value Beans mg TESCO Value Beans hhhh

Kinetic Energy When causing an object to accelerate work has to be done. The force F = ma or a = F/m As we already know v 2 = u 2 + 2ax Therefore since u = 0… … … and Energy or Work Done = Fx v 2 = 2xF/m Fx = ½mv 2 Kinetic Energy = 1 / 2 mv 2 v2v2v2v2 TESCO Value Beans m

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 WEP Support  S&C Escalator  Practical 5.3 – Investigating GPE