Energy Energy and Work Energy is the ability

Energy

Energy and Work • Energy is the ability to do work • Whenever work is done, energy is transferred or transformed from one form to another. • Energy is measured in Joules (J).

Types of Energy • Kinetic energy • Potential energy • Mechanical energy- the sum of potential and kinetic energy in a system • Chemical energy- a type of potential energy found in atoms • Solar energy- from the sun

Potential Energy • Potential energy is stored energy – Also known as energy of position

Potential Energy • Gravitational potential energy exists between two objects separated by a vertical distance – For example, a rock sitting on top of a hill has potential energy compared to the ground beneath it. – Depends on both mass and height • PE = mass x free-fall acceleration x height PE = mgh

Potential Energy • Calculate the gravitational potential energy of a 0. 52 kg bird flying at an altitude of 550 m. PE = mgh = (0. 52 kg)(9. 8 m/s 2)(550 m) PE = 2800 J

Kinetic Energy • Kinetic energy is the energy of motion – Depends on both mass and speed • KE = ½ x mass x speed squared = ½ mv 2

Kinetic Energy • What is the kinetic energy of a 44 kg cheetah running at 31 m/s? KE = ½ mv 2 = ½ (44 kg)(312) = 21000 J

Roller Coaster Lab Report • Draw your roller coaster design. • Label whether KE and PE are increasing or decreasing on each segment of the roller coaster. • Answer the following questions: 1. Calculate the PE of the marble at the top of the roller coaster (use 0. 0013 kg as the mass of the marble). 2. Calculate the average velocity of the marble as it goes through your roller coaster (distance/time). 3. Use the velocity calculated to find the kinetic energy of the marble at the end of the roller coaster. 4. Was the PE equal to the KE? Why or why not?