Kinetic and Potential EnergyPhysics 6(B)

Learning Objectives• Explain the differences between kinetic and

potential energy and their sources• Describe situations involving kinetic and

potential energy• Explain how potential energy is transformed

into kinetic energy and kinetic energy is transformed into potential energy

Kinetic and Potential Energy

• Kinetic Energy (KE) – the energy of an object due to motion– Measured in joules, J

• Dependent on:– Mass (m )– Velocity (v)

Defining Kinetic Energy

• At the top, a skateboarder has no kinetic energy– Kinetic energy increases as the skateboarder

moves downwards and speeds up

• At the bottom, a skateboarder has maximum kinetic energy– Kinetic energy decreases as the skateboarder

moves upwards and slows down

Kinetic Energy

• Potential Energy (PE ) – the energy of a system due to its position– Measured in joules, J

• Dependent on:– Mass (m )– Height above ground (h )– Acceleration due to gravity (g )

Defining Potential Energy

• On the ground, each block has no potential energy

• On the stairs, the yellow object has the least potential energy and the green object has the most potential energy

Potential Energy

• Energy can be transformed from one type to another

• In the picture on the left, the ball’s potential energy is at a maximum and its kinetic energy is at a minimum

• In the picture on the right, the ball’s kinetic energy is at a maximum and its potential energy is at a minimum

Energy Transformation

• Transformation between kinetic and potential energy is never perfect– Energy can be “lost” when it is transformed out

of a system

• Some kinetic and potential energy of the roller coaster is transformed into heat and sound

Energy Transformation

Learning Objectives• Explain the differences between kinetic and

potential energy and their sources• Describe situations involving kinetic and

potential energy• Explain how potential energy is transformed

into kinetic energy and kinetic energy is transformed into potential energy

Kinetic and Potential Energy