Work = work is done when a net force on an object causes it to move a distance W = Fd Or Work (measured in joules) = Force (N) times Distance (m) Is work every done when there is no motion?

Power is the rate at which work is being done or how long it takes to do a certain amount of work - Power is measured in watts Power (watts) = work done (Joules) / time (s)

Energy is the ability of an object to do work -Mechanical energy is the energy an object has because of its position or because of its motion Kinetic Energy – the energy due to the motion of an object Potential Energy – the energy due to the position of an object or energy in a stored state

 What are the three different ways that an object can store energy - Elastic potential energy is the energy an object has because of its ability to bounce back to its original position

Chemical Potential Energy is the potential energy stored in chemical bonds of molecules like fuels. A reaction can release that energy so that it can do work or move things.

Gravitational Potential Energy is the energy an object has because it is elevated above the Earth. - this is how a water wheel works PE = mgh Gravitational potential energy (J) = mass (Kg) x gravity’s acceleration (m/s 2 ) x height (m)

Kinetic Energy is the energy of motion and it depends on the speed of the object and the object’s mass (or the objects momentum) KE = ½ mv 2 Kinetic Energy = ½ mass (Kg) x velocity 2 (m/s) Since kinetic energy is also the momentum of an object we can say; Fd = ½ mv 2 F stands for force in Newtons and d stands for distance moved in meters

Whenever work is done energy changes! Or Work = ∆KE

Energy is never created or destroyed it just changes forms (from potential energy to kinetic energy to light energy to heat energy to sound energy)

Machines transfer energy from one place to another or transform energy from one form to another. For all machines: work input = work output or (force x distance)input = (force x distance) output

If you use a lever to pry up a heavy object do you thing the work you put into the lever by pushing down is equal to the work done to lift the heavy object. - Yes because work is force times the distance moved

Lever and Fulcrum There are three types of levers: Type 1: The fulcrum is between the input force and the load Type 2: The load is between the fulcrum and then input force Type 3: The fulcrum is at one end and the load is at the other

 Inclined Planes – ramp - A screw is an inclined plane wrapped around a cynlinder

Pulleys is a type of lever that can be used to change the direction of a force - pulleys can be used to multiply forces

Simple machines allow a person to apply more force than they are pushing with. Mechanical advantage – the ratio of output force to input force for a machine If this man pushes down with a force of 30 N and lifts the rock that has a weight of 90 N, the mechanical advantage of the lever is 90N/30N =3

 All machines do not convert all the work input into work output. Some of the energy is converted to heat.  Efficiency of a machine is the ratio of useful energy output to total energy input Efficiency = useful work output / total work input