Work, Energy and Power

Introduction

Work can be defined as transfer of energy. In physics we say that work is done on an object when you transfer energy to that object. If one object transfers (gives) energy to a second object, then the first object does work on the second object. 

Work is the application of a force over a distance. Lifting a weight from the ground and putting it on a shelf is a good example of work. The force is equal to the weight of the object, and the distance is equal to the height of the shelf (W= Fxd).

Work-Energy Principle --The change in the kinetic energy of an object is equal to the net work done on the object. 

Energy can be defined as the capacity for doing work. The simplest case of mechanical work is when an object is standing still and we force it to move. 

What is Power?

Power is the work done in a unit of time. In other words, power is a measure of how quickly work can be done. The unit of power is the Watt = 1 Joule/ 1 second.

Calculating Work, Energy and Power

WORK = W=Fd 

Because energy is the capacity to do work , we measure energy and work in the same units (N*m or joules). 

POWER (P) is the rate of energy generation (or absorption) over time:P = E/t 

Power's SI unit of measurement is the Watt, representing the generation or absorption of energy at the rate of 1 Joule/sec.

Task

Evaluation

Answer the following?

  1. What is the formula for W?

  2. What is “JOULES”?

  3. What does Professor Dave mean when he says “work can be scalar”?

  4. Why is it important to identify + or - when referring to WORK?

  5. What is a watt?

  6. What is the "work" example that the intro gave you? 

  7. What is your example of "work" (speak in physics lingo)

  8. In detail, please explain how an object may NOT be in motion?  Provide example.

  9. Explain the process of energy transfer in regards to wind turbines (see book)

  10. Draw a diagram in your science copybook of energy transfer in

    1. Wind turbines (yes draw detailed pictures and LABEL)

    2. A baseball player hitting a ball (yes draw detailed pictures and LABEL)

  11. Raise your hand to show your pictures - they will be returned if not complete properly

Conclusion

Test on 12/11 :)