Positive/ Negative Work

[Hannah Fiel 2H]

4A.3 part b of the textbook problems asks if the work positive or negative with respect to the air pump that is compressed.

What makes work positive or negative?

[Armaan Judge 3L]

Work is essentially looking at the effects a system has on its surroundings. When the system does work on the surroundings, energy will leave the system, and work will be positive. If work is done on the system, energy will enter the system, and work will be negative. In this case, since the air is compressed, work is being done on it and will thus be positive.

[Richard Chiu 1I]

For this problem we have to look at work from the perspective of the system. Since the system is about the air available in bicycle pump, as it is compressed there is an input of energy into the system. As a result, we would view it as positive work done.

[Yasmine_B_1H]

Hello,

Work=the effect a system has on its surroundings.

When the system does work on its surroundings, energy leaves the system, so it is a positive value. When work is done on the system energy will enter and the value is negative.

In this problem air is compressed, it is on its surroundings so it will result in a positive value.