work, power and energy for grade 8 science .pptx

work, power and energy

1. SCIENCE 8 SCIENCE 8 QUARTER 1 WEEK 3 WORK, POWER and ENERGY

2. Review State the Second Law of Motion Newton's second law of motion states that  F = ma, or net force is equal to mass times acceleration. A larger net force acting on an object causes a larger acceleration, and objects with larger mass require more force to accelerate.

3. WORK Work is done when a force acts upon an object to cause a displacement .

4. Objectives Define work scientifically Identify situations in which work is done and in which no work is done.

5. Demonstration a. Student 1 pushes the blackboard. b. Student 2 pulls a chair from one end of the room to the other end. c. Student 3 pulls a chair then return it to its original place.

6. From the three demonstrations, which activity showed that work is done or no work done? Explain.

7. Activity Is there work done?

8. Guide Questions 1. Which of the four situations demonstrated or showed that work is done? Why? 2. Why do you think situation number 3 did not show that no work is done? Why? 3. What is the effect of the force the object?

9. Guide Questions 4. How will you relate the force and the direction of the motion? 5. When can we say that work is done?

10. Agree or Disagree !!! 1. Work does not necessarily mean physical labor. 2. If there is displacement in the same direction of the force then there is work automatically.

11. Agree or Disagree !!! 3. Work done at a very limited time frame means there is high power output. 4. If there is no force exerted, there won’t be any work output.

12. Agree or Disagree !!! 5. If force and distance move at an angle there is work one.

13. WORK Work is present when the force exerted causes an object to have a displacement in the same direction of the force.

14. Identify situations in which work is done and in which no work is done. Write W if the situation shows work and NW if no work. Lifting a box from the floor. Pushing against the wall. Pushing a box along the floor. Carrying a bag of grocery Raising a flag during the flag ceremony