Conservation-of-mechanical-energy.pptx..

Science

1. Basic energy IN MOTION: Potential Energy- stored energy of an object or energy held by an object. Kinetic Energy- is the energy on object has due to motion.

2. Conservation of mechanical energy MAY 08, 2024

3. Mechanical Energy MECHANICAL ENERGY is the sum of the kinetic energy , or energy in motion , and the potential energy , or energy stored in a system by reason of the position of its parts.

4. Two(2) kinds of Mechanical energy POTENTIAL ENERGY- is energy possessed by objects at rest in a certain height. Elastic Potential Energy- is the energy stored in a stretched or compressed elastic such as spring. Gravitational Potential Energy- is the energy possessed by the an object because of its location or position. Ex.

5. 2. KINETIC ENERGY- is the energy possessed by an object by virtue of its motion.

6. Observe… FIGURE 1 FIGURE 2 When the ball is on the top it has potential energy , however as it start to fall, the potential energy is slowly converted to kinetic energy . When the ball touches the ground, there is no more potential energy and kinetic energy.

7. At Point 1, the PE is at its maximum due to its height or position. As the pendulum starts to move, the PE decreases while KE increases because of the change in position. At Point 2 , half of the PE is lost and becomes KE. Hence, PE is equal to KE (PE=KE) At Point 3 , the height of the pendulum is at the minimum, thus PE is also at the minimum, while KE is at the maximum. From Point 4 to Point 5 , the reverse will happen. It shall start with maximum KE at Point 3 . The KE will slowly transforms to PE. Eventually, potential energy is at maximum while KE is at minimum in Point 5 .

8. Any loss of potential energy or kinetic energy will result into a gain in kinetic or potential energy. There is no loss of energy in the system and energy is conserved . Therefore, the total mechanical energy at any point in pendulum is constant .

9. The sum of potential and kinetic energy is called TOTAL MECHANICAL ENERGY . ME T = PE + KE w here ME T = TOTAL MECHANICAL ENERGY PE = Potential energy; and KE = Kinetic energy J = JOULES  

10. For GRAVITATIONAL POTENTIAL ENERGY of an object. It is determined by this equation: PE GPE = mgh w here PE GPE = GRAVITATIONAL POTENTIAL ENERGY m = mass g = acceleration due to gravity (9.8 m/s 2 ) h = height

11. For KINETIC ENERGY OF AN OBJECT , it is determined by this equation: KE = mv 2   w here KE = KINETIC ENERGY m = mass v = velocity

12. Example: g= 9.8 m/s 2

13. Given: m= 3kg g= 9.8 m/s 2 h= 8m v= 0 m/s Formula: PE = mgh Solution: PE = (3kg)(9.8 m/s 2 )(8m) PE = 235.2 J Formula: KE = ½ mv 2 Solution: KE= (0.5)(3kg)(0 m/s) 2 KE= 0 J Formula: ME T = PE + KE Solution: ME T = 235.2 J + 0 J ME T = 235.2 J

14. Drill: 1. A 10kg ball is thrown downward at a speed of 14 m/s from a cliff that is 700 meters above ground. What is the mechanical energy of the ball?

15. Drill: 2. A 5 kg block is thrown downward at a speed of 10 m/s from a cliff that is 500 meters above ground. What is the mechanical energy of the block?

16. Figure 1

17. Quiz time: At which point has the highest Potential Energy in position A, B, and C? At which point has the highest Kinetic Energy in position A, B, and C? What is the formula for gravitational potential energy? What is the formula for Kinetic Energy? What is the formula for Mechanical Energy?

18. Fill in the blank: It state that any ______ (loss, gain, transfer) of potential energy or kinetic energy will result into a ______ (loss, gain, transfer) in kinetic or potential energy. There is no loss of energy in the system and energy is ______ (waste, conserved, dissipate) . Therefore, the______ (total, difference, partial) mechanical energy at any point in pendulum is ______ (unsteady, changing, constant) .

19. Answer: Position A Position B PE GPE = mgh KE= ½ mv 2 ME= PE+KE l oss gain c onserved t otal constant

20. assignment: Calculate the PE of in position A, B, and C. Cite one real-life scenario of conservation of mechanical energy. m= 5kg