Work, Energy and Power Conservation of Energy & Work Done

Objectives Apply the principle of the conservation of energy to new situations or to solve related problems Apply the relationships for kinetic energy and potential energy to new situations or to solve related problems Recall and apply the relationship work done = magnitude of a force x the distance moved in the direction of the force Understand the relation between work done and energy change Recall and apply the relationship power = work done/time taken to new situations or to solve related problems

Apply the principle of the conservation of energy to new situations or to solve related problems

Apply the relationships for kinetic energy and potential energy to new situations or to solve related problems

Recall and apply the relationship work done = magnitude of a force x the distance moved in the direction of the force

Understand the relation between work done and energy change

Recall and apply the relationship power = work done/time taken to new situations or to solve related problems

Conservation of Energy - Trebuchet Where does the potential energy in the lever arm come from? What are the energy changes that take place throughout the loading, cocking, and releasing of the trebuchet? What evidence is there that energy is conserved?

Where does the potential energy in the lever arm come from?

What are the energy changes that take place throughout the loading, cocking, and releasing of the trebuchet?

What evidence is there that energy is conserved?

Conservation of Energy – Simple Pendulum Why was the pendulum unable to hit the face? What are the energy changes? Video

Conservation of Energy – Example 2 0.800 m 0.900 m 1.000 m

Work Done Work is said to be done when a force produces a displacement of an object. Scalar Quantity Work Done = Force x Distance moved in direction of force Unit: Joule(J) or Newton Metre (Nm)

Work is said to be done when a force produces a displacement of an object.

Scalar Quantity

Work Done = Force x Distance moved in direction of force

Unit: Joule(J) or Newton Metre (Nm)

Power Rate of doing work P = W/t or ∆E/t Unit: Watts (w) or Joule per second (J/s)

Rate of doing work

P = W/t or ∆E/t

Unit: Watts (w) or Joule per second (J/s)

Efficiency – Hydroelectic Plant Video

Efficiency