h = 4m
Mr. An and older brother Dung drag tablets brick go up high . I say tablets brick there Yes muscle capacity . So muscle power what is that ?
Lesson 21 – Lesson 16:
FUNCTION
Session 21 – Lesson 16: MECHANISM
I. Mechanical power
Session 21 – Lesson 16: MECHANISM
I. Mechanical power
- Being a form power quantity single simple most .
- When a object Yes ability power real presently labour muscle learn Objects _ Yes muscle capacity .
- When muscle power claw big gas object Yes ability power real presently labour muscle learn claw big .
- Body power Okay measure is equal to single taste jun , sign nicknamed J

Session 21 – Lesson 16: MECHANISM
II. Position power
1. So power steam guide
- Weight A stands at rest on the ground, unable to generate work
=> No chance
GROUND
Session 21 – Lesson 16: MECHANISM
II. Position power
1. So power steam guide
C1: If weight A is raised to a certain height, does it have potential energy? Why?
s 1
s 1
Yes. Since the weight is moving downwards, tension in the string pulls the piece of wood B to move, that is, to do work. So the weight has potential.
=> Weight A does the work
=> Heavy fruit A has potential
=> Mechanical energy in this case is called potential energy
Session 21 – Lesson 16: MECHANISM
II. Position power
1. So power steam guide
- If weight A is raised to any greater magnitude, will its mechanical energy change?
s 2
s 1
Answer:
=> The potential energy of an object depends on the height of the object
Session 21 – Lesson 16: MECHANISM
II. Potential energy
1. Gravitational potential
- Potential energy is determined by the height of the object above the ground => Gravitational potential energy.
When the object is on the ground, the gravitational potential energy is 0 .
Attention:
- Gravitational potential energy depends on the height datum
You can choose an arbitrary cap point
- Gravitational potential energy depends on the mass of the object
=> The more mass an object has, the more potential energy it has
II. Potential energy
2. Elastic potential energy
C2: How do we know if the spring has mechanical energy?
Session 21 – Lesson 16: MECHANISM
Answer:
- I cut or burn the rope. At that time, the spring springs up, pushing the piece of wood up
Spring does work => Spring has mechanical energy
The mechanical energy in this case is called potential energy
II. Potential energy
2. Elastic potential energy
- Potential energy depends on elastic deformation => called elastic potential energy
- The more compressed the spring, the more work the spring produces => the greater the potential energy of the spring


Session 21 – Lesson 16: MECHANISM
III. Kinetic energy
1. When does an object have kinetic energy?
Experiment 1: Let the steel ball A roll from position (1) on the inclined chute down and hit the piece of wood B

Session 21 – Lesson 16: MECHANISM
III. Kinetic energy
1. When does an object have kinetic energy?
C3: How will the phenomenon happen?


Answer:
Ball A rolls down and hits wood B, causing block B to move
Session 21 – Lesson 16: MECHANISM
(first)
S 1
III. Kinetic energy
1. When does an object have kinetic energy?
C4: Prove that the sphere A
moving is capable of real
present work.


Answer:
Sphere A exerts a force on a piece of wood B, causing the piece of wood B to move a distance, that is, work is done.
Session 21 – Lesson 16: MECHANISM
(first)
S 1
III. Kinetic energy
1. When does an object have kinetic energy?
C5: From the results of the experiment, find the right word for the place of the conclusion:

A moving object has the ability ………… ie has potential energy.

=> The mechanical energy of an object due to its motion is called kinetic energy
Session 21 – Lesson 16: MECHANISM
work
III. Kinetic energy
2. On what factors does the kinetic energy of an object depend?
Experiment 2: Let ball A roll on an inclined chute from position (1) position (2) higher than position (1) to hit (2) wooden pieces
Session 21 – Lesson 16: MECHANISM
(first)
III. Kinetic energy
2. On what factors does the kinetic energy of an object depend?
TN3: Replace sphere A with sphere A` with
larger volume and for rolling on
trough tilted from position (2), hit
piece of wood
Session 21 – Lesson 16: MECHANISM
(2)
III. Kinetic energy
2. On what factors does the kinetic energy of an object depend?
C7: What is the difference between the phenomenon that occurs?
Test 2? Compare work done
of two spheres A and A`. Thence inferred
kinetic energy of
extra ball
belong to how?
into its volume?
Session 21 – Lesson 16: MECHANISM
(2)
S 2
S 3
- When a ball A` is replaced with a larger mass, the piece of wood B is pushed further away upon impact.
- The work done by sphere A` is greater than the work done by sphere A.
- The kinetic energy of the auxiliary body increases proportionally to the mass of the object
III. Kinetic energy
2. On what factors does the kinetic energy of an object depend?
C8: The above experiments show that kinetic energy depends on what factors and how?
Kinetic energy depends on two factors: the mass of the object and the speed of the object
- When the mass of the object remains the same, if the velocity increases, the kinetic energy also increases (kinetic energy is proportional to the square of the velocity).
When velocity is constant, kinetic energy is proportional to mass.
Session 21 – Lesson 16: MECHANISM
IV. Manipulate
C9: Give an example of an object that has both kinetic and potential energy.
Session 21 – Lesson 16: MECHANISM
Flying pigeons
Grapefruit swinging on the branch
Aerobatics in the air
IV. Manipulate
C10: What kind of mechanical energy does the mechanical energy of each object in Figures 1, 2, and 3 belong to?
Session 21 – Lesson 16: MECHANISM
Elastic potential energy
Kinetic energy
Gravity potential
Gravity potential



The bow was raised.
Water flows from above.
The water is blocked on the high dam.
Which of the following objects has no potential energy?
A. The bullet is flying.
B. The spring is left at a natural height above the ground.
C. The marble is rolling on the ground.
D. The spring is forced to rest on the ground.

Select Size
So potential energy is determined by the height of the object above the ground. When the object is on the ground, the potential energy is 0 .
Lesson 16.10 / 46 SBT An object of mass m is raised to a height h and then dropped.
a) Calculate the work done by the object until it hits the ground.
b) Make a formula for the potential energy of the body at height h.
Prize
a) The work done by the object until it hits the ground is: A = P × h = 10m × h
b) The formula for the potential energy of an object at height h:
W t = P × h = 10m × h
Lesson 16.4 (page 45 Physics Workbook 8) The hammer hits the nail, causing the wood to sink deep into the wood. What energy does the nail sink deep into the wood? What form of energy is that?
The hammer hit the nail, flooding it deep into the wood. The nail sinks deep into the wood thanks to the energy of the hammer. That is kinetic energy.