What is Energy? Energy is the ability to do work In other words, energy is transferred by a force moving an object through a distance (Work = Force x Distance) Ability to cause change Can change itself or its surroundings Measured in Joules (J)

Energy & Work Work is the transfer of energy Example: carrying your backpack up the stairs You do work on the backpack by lifting it against the force of gravity…which requires energy The energy to do the work comes from your muscles Muscles receive energy from the food you eat Energy in food comes from plants that have used energy of sunlight, or animals that have eaten such plants

Kinetic Energy Energy of motion Depends on 2 factors: Mass Speed (velocity) What would happen to KE if we doubled the mass? KE would double What would happen to KE if we doubled the speed? KE would quadruple Why was KE highest at bottom?

Calculating KE A.10 kg bird is flying at a constant speed of 8.0 m/s. What is the bird’s KE?

Potential Energy Potential energy is energy that is stored as a result of position or shape Has the potential to do work 2 forms of potential energy Gravitational potential energy Elastic potential energy

Gravitational Potential Energy GPE depends on height, mass, and gravity What happens to GPE the higher the object is? increases m= mass (kg) g= gravity = 9.8 m/s 2 h= height (m) Usually relative to the ground or surface object is usually on

PE depends on where you are considering the reference line to be Has to be relative to something

Elastic Potential Energy Potential energy of an object that is stretched or compressed Something is said to be elastic if it springs back to its original shape after it is stretched or compressed

Forms of energy Forms of Energy Mechanical Thermal chemical electrical electromagnetic nuclear Associated with motion and position of objects Sum of PE and KE Speeding trains, bouncing balls, sprinting athletes Motion of the particles in matter Faster the particles are moving, more thermal energy Slower they’re moving, less thermal energy energy stored in chemical bonds Energy stored in atomic nuclei Form of energy that travels through space in the form of waves Energy associated with electric charges

What are some forms of energy you notice around the room?