1. Work and Power

2. What is force? A force is a push or a pull.

3. Work and Power

4. Work is the use of force to move an object some distance. Work is done only when an object that is being pushed or pulled actually moves.

5. Work is done. Work is being done because the force and motion are in the same direction Applied Force Direction of motion

6. Work is not done. Work is not being done because there is not movement of the box. Applied Force No motion

7. Calculating Work Work = force (N) x distance (m) Joules= Newton x meters remember that Joules is also the unit for energy, so work must be a form of ENERGY. Work = Energy

8. How much work is done if a person lifts a barbell weighing 450 N to a height of 2 m? –F= 450 Nd=2 m –W=F*d –W= (450 N) *(2 m) –W= 900 N-m –W= 900 J

9. Power is… Power= Work ( or Energy) Time P= E t The unit for power is the watt (W). One Watt equals one joule per second.

10. An Antarctic explorer uses 6000 Joules of work to pull his sled for 60 sec. What power does he need? –Work: 6000 Jtime: 60 sec –P= W/t –P= 6000 J/ 60 sec –P= 100 J/sec –P= 100 W

11. work transfer transferred the object energy time When you do work on an object, you transfer the energy of that object. Energy is transferred from yourself to the object. Power is equal to the amount of energy transferred over a certain time.

12. Consider an active sport. Describe the work being done by people as they play that sport.