Postive vs. negative work

[Jonathan Batac - 2D]

Can someone explain the concept that when work is being done by the system, it should be a negative value; and while when work is being done to the system it should be a positive value?

[Chloe Little 3K]

When work is done by a system, the system is using energy, meaning that energy is being released from the system to the surroundings, which is why work is negative. When work is done to a system, the system is gaining energy from the surroundings, so work is positive.

[Samuel Flores 1E]

Hello! When work is being done on the system, energy is being transferred into the given system, which means that the system is obtaining energy from the external work being applied. This allows the work to be positive when work is applied on a system, since it is obtaining energy.
On the other hand, when the system is performing work, it is losing energy as the system applies this work, thus losing energy in the form of work. Therefore, the work will be negative due to a loss in energy in the form of work.

Hope this helps!

[IshanModiDis2L]

When work is done by a system, the system is using energy, meaning that energy is being released. This makes work negative. When work is done to a system, the system is gaining energy, so work is positive.

[KhanTran3K]

Hey, when work is being done by the system, it would be a negative value since the system is using energy and it is being transferred to the surroundings. When work is being done on the system, energy is transferred from the surroundings to the system which account for the positive work value since it is gaining this.

[gabbi_r2C]

I agree with everyone before; if work is done by the system, then the system uses (ie loses) energy, so the value for work is negative--dont forget that energy is always in terms of the system, not the surroundings. Thus, work done on the system (by something else) is the opposite, and is positive because the system gains energy.

[FionaHunter21]

Doing work requires energy, so when the system does work, it loses energy, just like humans would lose energy from doing physical work. When work is done on the system, that energy is transferred from the surroundings to the system, meaning it would gain energy.

[Madeline Louie 1B]

When work is done by the system, the value should be negative because the system is losing energy due to doing work. When work is being done on a system, the value is positive since energy is going into the system.

[Kyle Dizon 3A]

From how I understand it, you can think of yourself as riding a bicycle. In order to achieve greater speeds, you would have to pedal meaning, you are doing work therefore losing energy (-w). Then, when work is done for you when you are going downhill (surroundings) you gain energy. Hope this helps!

[Sofia Lombardo 2C]

If the value of work is positive, then work is being done ON the system. Since energy is used when a system does work, work done BY a system should have a negative value.

[Sheryl Ocampo 1D]

When work is being done by the system, energy is leaving the system making it negative. When work is being done to the system, energy is being absorbed by the system, making the value positive

[Melis Kasaba 2B]

Work is a measurement of internal energy in chemistry. When work is done ON the system/heat is given to the system, its internal energy increases and the work is positive. If work is done BY the system/heat is given off, its internal energy decreases and the work is negative.

[Gerardo Ortega 2F]

A system uses energy to do work (it loses energy when doing work), and that energy gets replaced by heat flowing into the system (q = -w).

[Lauren Sarigumba 1K]

when work is done on the system, this means that there is compression. therefore, the internal energy is increasing, and the change in internal energy would be positive. When work is done by the system, there is expansion. Therefore, the internal energy is decreasing, and the change in internal energy would be negative.

[Jiapeng Han 1C]

Basically, when you compress something, work done is positive. When something expands, the work done is negative. The reason being that when you do work to the system(ex. compressing a gas), the system gains energy so work done is positive. When the system itself does work(ex. when gas expands), the system loses energy so work done is negative.

[Justin Lin 1B]

When work is being done by a system, that means the system is losing energy and makes work (w) negative. If work is being done on a system, the surrounding is losing energy and that energy is being gained by the system, making work positive.

[Alisa Nagashima 1B]

Work would be negative when the system is doing work because it is losing energy to the surroundings. Likewise, if work is being done on a system by the surroundings then work would take a positive value because it is gaining the energy that the surroundings lost.

[Andersen Chu 2H]

The sign of w is relative to the system. When a system is doing work, it loses energy (just like a human would lose energy if they are doing some work like lifting a weight) so w is negative. When work is done on a system, it is receiving energy so w is positive and increasing.

[Jason_John_2F]

work is negative when the system is doing work because the energy is lost to the surrounding and work is positive when work is being done on the system because the system is gaining energy