» Energy cannot be created or destroyed! » Energy is transformed from one form to another » The sun radiates energy in the form of waves, plants transform this energy into chemical energy, then animals eat these plants and use this energy for kinetic energy. » There are two categories which all forms of energy and be put in Kinetic Energy and Potential Energy
» The energy of motion » Depends on mass and velocity » There are many forms of motion: ˃Objects (people moving, falling rocks, planets revolving) ˃Waves (light waves, microwaves, Ultra Violet) ˃Electrons (flowing through a wire, revolving around an atom) ˃Atoms (vibrating due to temperature)
» Velocity- rate of change of displacement ˃Measures how an objects position changes over time ˃Distance divided by time (m/s) ˃Meters per second » Mass- quantity of matter in an object. ˃Measured in kilogram (kg) kilograms
A baby has a ball and rolls it across the ground The ball’s mass is 3 kg The ball is moving at 2 m/s. What is the ball’s total energy?
» Mass= 3 kg (kilograms) » Velocity = 2 m/s (meters per second) Kinetic energy = 1/2mv² = mass X volume² (3kg)(2m/s)² = 6 kg*m²/s² meters seconds 2
» Stored energy and the energy of position » There are 2 types of potential energy ˃Gravitational Potential Energy ˃Elastic Potential Energy (springs, rubber bands)
» Gravitational Potential Energy = mgh (mass x acceleration due to gravity x objects height) Acceleration due to gravity = 9.8 m/s² A baby rolls a ball example extended: » Mass= 3kg » Gravity = 9.8 m/s² » Height = ? » What is the balls potential energy? » What is the balls total energy? (KE + PE = Total Energy)
Think about a 3 kg ball being thrown straight up in the air. When the ball is released it only has kinetic energy. What is the velocity of the ball when it reaches its highest point? Does the ball have any kinetic energy at the highest point? Once the 3 kg ball reaches its highest point it is 10 meters above the ground. What is the balls potential energy at this point? (mgh, mass x gravity x height = Gravitational potential energy)