The necessary factors to judge whether an object has done work or not are:

In order to determine whether a force is doing work on an object, two necessary conditions must be met at the same time:

1. The force acting on the object;

2. The object passes a distance in the direction of the force.

To figure this out, you also have to figure out three situations in which force does not do work on an object:

1. Powerful no distance: pushing the cart hard without pushing - no effort;

2. There is distance and no force: objects that move due to inertia (shot put that is pushed out, football that is kicked out. Nothing to do;

3. The force is perpendicular to the distance: the object is carried to move on the horizontal plane.

You can see the formula for doing work! w=fs

f is the force acting on the object, s is the distance that the object moves under this force f, you must pay attention to this s, that is, displacement, for example: you pull the object to the right and move s, then the work done is w = fs, the displacement must be in the direction of the force, there is a very classic problem is to play football, a person kicks a football for example, 300m, ask the person to the ball work At this time, you can't follow w = fs, because after the human foot gives the football a force, the football moves forward by inertia, Although there is displacement, the football is only subject to gravity and air resistance during flight, so you need to fully understand the definition of work If you don't understand, you can ask me

Forced. The distance was shifted in the direction of the force.

It moves a distance in the direction of the force, for example, if something falls from a height, then it has a distance in the direction of gravity downward, so gravity does the work.

The direction of the force is not perpendicular to the direction of motion.

Regarding the power of the work done by the object, the following statement is true ( A The shorter the work time of the object, the greater the power b The more work the object does, the greater the power c The slower the work done by the object, the greater the power d The faster the work done by the object and the greater the power.

There are two necessary factors for work to be done: one is the force acting on the object, and the other is the distance traveled in the direction of the force

So the answer is: one is the force acting on the object, and the other is the distance that moves in the direction of the force

Regarding the power of the work done by the object, the following statement is true ( A The shorter the work time of the object, the greater the power b The more work the object does, the greater the power c The slower the work done by the object, the greater the power d The faster the work done by the object and the greater the power.

First of all: the object does not do work, only the force on the object does the work......1.A certain force on an object: see if this force produces a displacement on the line on which it acts, the force is perpendicular to the displacement, then no work is done, otherwise work is done.

2.Combined external forces: Same as above, see whether the vector sum of the external forces of the system is perpendicular to the displacement.

3.Combined internal forces: The combined internal forces of an object are always not done (except for gases) Exception: Frictional work is done: The work done by frictional force requires that the frictional force be multiplied by the distance and not by the displacement.

Judging from the necessary elements of work: 1. Do the force used on the object. 2. The distance the object moves in the direction of the force. Indispensable.

Example: 1. A child can't move a big rock, "I can't afford to move". Because there is no distance. So don't do the work. "Nothing to Gain".

2. Slide the ice cube in the extremely smooth horizontal direction, move forward by inertia, although the distance has passed in the horizontal direction, but there is no force in the horizontal direction acting on it, so there is no force to do work. "No Effort".

Not necessarily.

This sentence does not mean that the internal energy of the work done to the object must increase, or the internal energy of the external work of the object must decrease. For example, when an object is lifted, the object only increases the gravitational potential energy, but does not increase the internal energy. An object that is lifted accidentally falls and hits you, and the work done by the object on you only reduces the mechanical energy, but does not reduce the internal energy.

The internal energy of an object should include the sum of energies such as kinetic energy, potential energy, chemical energy, ionization energy, and nuclear energy inside the nucleus of all the microscopic particles in it.

However, in the process of changing the general thermodynamic state, the molecular structure, atomic structure and nuclear structure of matter do not change, so these energy changes can not be considered. But when chemical reactions are involved in thermodynamics research, chemical energy needs to be included in the internal energy.

When an object does work externally, the energy it has will decrease, but the internal energy does not necessarily decrease, but many objects do work externally, and the internal energy will increase, such as the electric fan will produce heat (electrical energy is converted into the kinetic energy and internal energy of the fan blade), in fact, many objects do work externally, and the internal energy will increase, and the increase in the internal energy of the bullet hitting the wooden stake seems to be problematic, because the increase in the internal energy of the bullet is that the gas produced by gunpowder does work on the bullet to increase its internal energy.

Of course not, if you think about the bullet hitting the stake, the internal energy will increase.

There are two necessary factors for doing work: one is the force acting on the object; The second is the distance the object moves in the direction of the force

So the answer is: force; The distance traveled in the direction of the force

There are two necessary factors for doing work: one is the force acting on the object; The second is the distance the object moves in the direction of the forceIn physics, it is stated that the work done by a force on an object is equal to the product of the force and the distance

So the answer is: the force acting on the object; the distance the object moves in the direction of the force; The product of force and distance

The work spoken of in mechanics consists of two necessary factors: one is the force acting on the object, and the other is the distance that the object passes in the direction of the force.

The so-called necessary factors mean that these two factors are indispensable, if they are missing.

One of the factors, from the point of view of mechanics, is that no work has been done, so it can be seen that these two factors are judged by us.

The only basis for determining whether an object does work or not.

Therefore, to judge whether a force has done work or not, it must be acted on the object.

and whether the object passes distance in the direction of the force is considered in both aspects.

Determine whether the object is doing work.

Meaning the following points:

1 Whether the force acting on the object causes the object to move a distance in the direction of the force. If the force acts on the object, but the object does not move, i.e., f≠

0, s=0, then.

w=fs=0

Do not do work. For example: push one.

The sedan stuck in the mud was not pushed.

In this example, although the force acts on the object, the object does not.

When a distance is passed in the direction of the force, it is said in mechanics that no work has been done, which is "work without work".

2 Whether an object is moved a certain distance under the influence of a force. If there is no force acting on the object, but the object moves due to di-inertia, ie.

f=0，s≠

0, then w=fs=0

Do not do work. For example: one in a smooth one.

The shot put that slides on the horizontal ground is moving due to inertia, and although it passes the distance in the horizontal direction, there is no force acting on it, so there is no force to do work, which is "no work".

3 Whether the distance the object has traveled is in the direction of the force. If the force acts on the object, and the object also moves, but the direction of the object's motion is perpendicular to the direction of the force experienced, i.e., the object does not have in the direction of the force.

The distance traveled, i.e., f≠

0, s=0, then.

w=fs=0

Do not do work. For example, a person carrying a bucket of water is walking on a horizontal road.

walk, the bucket moves forward in the horizontal direction, and the force of the person on the bucket is vertically upward, while the bucket moves.

The distance is horizontal, and it does not move upwards, and there is no distance in the direction of the force, which is also "labor without effort".

The work done physically must be moved a certain distance in the direction of the force under the action of the force.