How many lessons should I take on the kinetic energy theorem, kinetic energy and the kinetic energy

The kinetic energy theorem can be discovered experimentally first and then proved by calculation! Personally, I think physics is built on thinking and doing! Let's do the experiment!

So that we have a substantial understanding of the theorem! In the relationship between theorems and theorems can be established by proof! For example, this experiment can establish the interconnection between Newton's laws, momentum theorem, kinetic energy theorem and work!

Enliven our mind!

Also, I don't think it is possible to prove the kinetic energy theorem using Newton's laws alone. It is also necessary to use the knowledge of the momentum theorem, which is my point of view. You can prove it yourself.

Finally, it is not very good to calculate the displacement by passing the paper tape! Experiments need to be precise! Air cushion rails can be considered

The formula of the kinetic energy theorem can be deduced from the perspective of dynamics, and then experimentally verified.

This is the inductive method, and high school students are easy to accept new knowledge.

You can also do an experiment first and get mgh=1 2mv 2 and let the students guess w=delta ek

It is then proved by theoretical derivation.

This is a deductive approach that can make the lesson more in line with the ideas of the new material.

Method 1: It is easy to control the pace of the class, and there is plenty of time to supplement the practice, but it lacks new ideas.

Method 2: It is easy to adjust the classroom atmosphere, and there is more interaction between teachers and students, but the time may be tighter.

Generally, 2 class hours are arranged, and one class hour is arranged for kinetic energy and one class hour for kinetic energy theorem.

What does it mean to be slow? If it is a uniform motion, then the resultant external force is 0 (the tensile force is numerically equal to the frictional force). If it is a uniform acceleration motion, even if the amount of change is small, the amount of change in kinetic energy is not 0, which is equal to the work done after subtracting the frictional force from the tensile force.

Kinetic energy theorem: work done by an external force = change in kinetic energy.

The object in your question must be moving at an accelerated pace (friction is zero, only kinetic force) and the kinetic energy change cannot be zero!

If it's a rough support surface:

Tensile force f = frictional force f

The combined external force = 0, and the kinetic energy increment is equal to zero.

The power is all used to overcome the resistance, not to increase the kinetic energy.

There is something wrong with the assumptions of the question.

It is impossible to move a certain distance with a slow horizontal pull of a rope on a smooth horizontal surface, a=f m

v 2=2as kinetic energy ek=1 2mv 2=fs, neither the work done nor the kinetic energy change is 0

If it is a rough horizontal surface, pull an object slowly and horizontally with a rope and the acceleration is 0 f-f=0=f.

fH s=0=ek The kinetic energy is unchanged.

Work-energy theorem. The so-called kinetic energy, simply put, refers to the energy possessed by the motion of an object. Numerically equal to (1 2) mv 2.

Kinetic energy is a type of energy, and its unit under the International System of Units is joules (j), referred to as joules. It is important to note that kinetic energy (and the various works corresponding to it) is a scalar quantity, i.e., there is only magnitude and no direction. When summing, only its algebraic sum is calculated, and the parallelogram rule of vector (called vector in mathematics) addition is not satisfied.

First of all, you have to know the distance at which it accelerates, and then there is only friction in that distance, i.e. umgl = 1 2 m v 2 l is the acceleration length.

The kinetic energy theorem states that the work done by an external force on an object is equal to the change in the kinetic energy of the object.

The content of the kinetic energy theorem: The total work of all external forces on an object, (also called the work of the resultant external force) is equal to the change in the kinetic energy of the object.

Mathematical expression of the kinetic energy theorem:

Turn left|Turn right.

The work done by the force on the object in a process is equal to the change in the kinetic energy of the object in that process.

The so-called kinetic energy, simply put, refers to the energy possessed by the motion of an object.

The workmanship of the combined external force is equal to the increment of kinetic energy.

First find out all the combined external forces, judge the positive and negative of the workmanship, and write it on the left side of the equal sign; Then write OK on the right side of the last kinetic energy minus the initial kinetic energy

In the process, the total work done by the combined external force is equal to the amount of change in the kinetic energy of the system.

As long as there is the total work of the combined external force, there is also the initial kinetic energy and the final kinetic energy.

For the resultant external force, there can be a force analysis such as push or tension, friction force, etc.

1. Use the kinetic energy theorem to find the work of variable force

In some problems, due to the change of the magnitude or direction of the force f, it is not possible to directly use w=fscos to solve the value of the work done by the variable force f, and the result of the work done by it can be solved by the change of kinetic energy.

2. When using kinetic energy to solve the problem, if the object contains several sub-processes with different motion properties (such as acceleration and deceleration) in a certain motion process, at this time, it can be considered in sections or in the whole process.

3. The work done by friction is related to the path.

Can this be explained directly? Unless you give more details.

Kinetic energy theorem content: The work done by the combined external force is equal to the change in the kinetic energy of the object.

Expression: where ek denotes the final kinetic energy of the object and ek0 denotes the initial kinetic energy of the object. EK is the change in kinetic energy, also known as the increment of kinetic energy, and also indicates the total work done by the resultant external force on the object.

1.The object of the kinetic energy theorem is a single object, or a system of matter that can be called a single object.

2.The calculation formula of the kinetic energy theorem is an equation, and the ground is generally used as a reference frame.

3.The kinetic energy theorem applies to the linear motion of an object as well as to the curvilinear motion; It is suitable for constant force work, and also suitable for variable force work; Forces can act piecewise or simultaneously, as long as the sum of the positive and negative algebraic numbers of each force can be found, which is the superiority of the kinetic energy theorem.

Application: (1) Determine the research object, which can be a particle (monomer) or a system.

2) Analyze the force and motion of the research object, whether it is a problem to solve the "relationship between force, displacement and velocity".

3) If yes, solve according to the w=ek column.

The kinetic energy theorem can be used to solve the problem of linear motion as well as the problem of curvilinear motion. When applying, pay attention to which forces do work, how much work is done, what is the initial kinetic energy, and what is the final kinetic energy. Then solve for the column equation – the work done by the combined external force is equal to the increment of the kinetic energy of the object.