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# Mass needed for work?

Do you need to know the mass of moving objects to calculate work?

### 3 Answers

- 1 decade agoFavorite Answer
work= - potential

or

work = force times distance

you dont need the mass to calculate work......if you have force and distance or potential energy

- ☼¿☼Lv 51 decade ago
Not nessecarily, it depends on the info given. Work by definition is Force * distance. So if you are told that a certain force was applied to an object and the object moved a distance which is also given, then no you don't need the mass. In most cases though, you will need the mass to calculate either the force or the distance, or you will need to find the work done by using the conservation of energy, in which case you'll need the mass to calculate how much energy was transferred.

For example, if I apply a force of 10N to a box over a distance of 4m, then no matter what the mass is, the work will be

W=F*d

=10*4

=40J

However if you need to find the work done on an object to get it to a speed of 4m/s, but are not given a force, you will need a mass, and you can then calculate its kinetic energy, which will be the work done.

Ek=mv^2/2

So we need a mass. if the mass is 5kg, then

Ek=(5)(4)^2/2

=80/2

=40J

So it is only nessecary if the situation calls for it.

- 1 decade ago
Not if you know the change in kinetic energy.

W = FD or Delta K

Source(s): I'm a physics teacher