Calculating Work Done by a Push: Weight vs Push Forces

[kaweezah]

my teacher gave the class a quiz and one of the questions was to calculate the work done. the formula for work is force x distance. my problem was that their were two forces given, the weight and the exerted push.. which one should i have used?

 

[Doc Al]

Which way is the object moving? The only force that contributes to the work on an object is the component in the direction of the object's displacement.

 

[pixel01]

You should take into account the force portion which is in the same direction of the movement. Anyway, it is better to describe the scenario more in detail.

 

[kaweezah]

so if the displacement is downward i use the weight and if it's horizontal i use the push. am i getting the idea correctly?

 

[Doc Al]

so if the displacement is downward i use the weight and if it's horizontal i use the push. am i getting the idea correctly?

That's right, but be sure to read the question carefully. They are probably asking for the work done by the push (not the work done by all forces). If so, the weight is irrelevant regardless of how it moves.