1. Energy  Energy is conserved!  not created.  not destroyed,  may change type  may be transferred from one object to another.  One way to transfer energy is through work

2. Work  Work is the transfer of energy to an object by applying external force.  Work is not a vector. It has a sign, but no direction in space.  The work done by a force, on an object,  is positive if the force is giving energy to the object.  is negative if it decreases the object’s energy

3. Kinetic and Potential Energy  The kinetic energy of an object, moving at speed, v is  The gravitational energy of an object, at height h is

4. Conservation of Energy  The work-energy theorem says  If no external force does any work on an object (or system), then W=0  The total energy of the object is unbchanged  Ef=Ei

5. Conservation Example A 1-kg weight is dropped from a height of 1 m. Another 1 kg weight is allowed to slide down a frictionless ramp from a height of 1m. Find the speed at the bottom in each case Use: Ui=9.8 J in both cases, Ki=0 in both cases. Uf=0 in both cases. Plug into eqn above Kf = 9.8 J in both cases =½ mv 2 Vf=4.4 m/s in BOTH CASES if it weren’t for friction, both masses would achieve the same speed