## Work

$\Delta U=q+w$

melissa_dis4K
Posts: 106
Joined: Fri Sep 28, 2018 12:28 am

### Work

How can you determine whether work was done by or on a system? Thank you.

Lauren Ho 2E
Posts: 70
Joined: Tue Oct 09, 2018 12:16 am

### Re: Work

If energy leaves a system, the system does work on its surroundings. If energy enters a system, work is done on the system.

Jessica Tsui 1H
Posts: 30
Joined: Fri Sep 28, 2018 12:21 am

### Re: Work

When work is done on a system, w is positive. When work is done by a system, w is negative.

Millicent Navarro 1I
Posts: 61
Joined: Fri Sep 28, 2018 12:25 am

### Re: Work

Personally, what helps me the most is by looking at the keywords the problem is giving me. For example, if I see "work being done", I automatically assume it is positive because there is energy being entered on a system.