# calculating work

## calculating force or distance when work is known

The work equation given above can be rearranged to find force or distance if the other variables are known: Force = Work Distance Distance = Work Force After Clarissa finishes mowing both lawns, she pushes the lawn mower down the sidewalk to her own house. If she pushes the mower over a distance of 30 meters and does 2700 joules of work, how much force does she use? Substitute the known values into the equation for force: J Force = 2700 30 m = 90 N Q: When Clarissa gets back to her house, she hangs the 200-Newton lawn mower on some hooks in the garage (see the Figure 1.1). To lift the mower, she does 400 joules of work. How far does she lift the mower to hang it? A: Substitute the known values into the equation for distance:

## how much work

The equation for work can be used to calculate work if force and distance are known. To use the equation, force is expressed in Newtons (N), and distance is expressed in meters (m). For example, assume that Clarissa uses 100 Newtons of force to push the mower and that she pushes it for a total of 200 meters as she cuts the grass in her grandmothers yard. Then, the amount of work Clarissa does is: Work = 100 N 200 m = 20,000 N m Notice that the unit for work in the answer is the Newton meter (N m). This is the SI unit for work, also called the joule (J). One joule equals the amount of work that is done when 1 N of force moves an object over a distance of 1 m. Q: After Clarissa mows her grandmothers lawn, she volunteers to mow a neighbors lawn as well. If she pushes the mower with the same force as before and moves it over a total of 234 meters, how much work does she do mowing the neighbors lawn? A: The work Clarissa does can be calculated as: Work = 100 N 234 m = 23,400 N m, or 23,400 J

## work force and distance

Work is the use of force to move an object. It is directly related to both the force applied to the object and the distance the object moves. Work can be calculated with this equation: Work = Force x Distance.

## instructional diagrams

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## questions

when calculating work, force is measured in

``````a) joules.

-->  b) newtons.

c) foot-pounds.

d) none of the above
``````

one joule equals the amount of work that is done when 1 n of force moves an object over a distance of

``````a) 1 cm.

-->  b) 1 m.

c) 1 km.

d) none of the above
``````

you can calculate force from work and distance with the equation

``````a) force = work x distance.

-->  b) force = work/distance.

c) force = distance/work.

d) force = work + distance.
``````

you can calculate distance from work and force with the equation

``````a) distance = work x force.

-->  b) distance = work/force.

c) distance = force/work.

d) distance = work + force.
``````

## diagram questions

No diagram questions associated with this lesson