What's Wrong with This Argument? Problem-Solving a Homework Statement

[Riddl3r]

Homework Statement

Our teacher made an unconvincing argument based on this example:
If a horizontal force of 15 N were a applied to a 2 kg block, and the work done was 20 J, what distance did the object move?

2. The attempt at a solution
Using W=F*d the teacher solved this: 20 J=15 N*x -> x=4/3 m.
This implied that if I applied 15 N to an object of any mass and did 20 J of work, the distance I could move the object is always the same. There seems to be something fundamentally wrong with this statement. But I'm not seeing what it is, I know it's there - I'm think that somehow I need to do something with the weight of the object. I mean if it were to be realistic I would have to calculate friction and gravity too...

Can somebody please tell me what I missed out?

 

[Doc Al]

You already posted this here: https://www.physicsforums.com/showthread.php?t=237998

 

[Moetasim]

There are a few issues with this argument.

Firstly, the equation W=F*d can only be used to calculate work done in a straight line when the force is constant. In this case, the force is not constant as it is being applied horizontally, which means that the distance traveled by the object may not be in a straight line. This means that the work done may not be accurately calculated using this equation.

Secondly, the statement assumes that the work done is solely due to the applied force of 15 N. However, there may be other forces at play, such as friction and gravity, which could also contribute to the work done. This means that the calculated distance may not be accurate as it does not take into account these other forces.

Additionally, the statement assumes that the mass of the object does not affect the distance it can be moved with a given amount of work. This is not always true as objects with different masses may require different amounts of work to be moved the same distance.

In order to accurately solve this problem, all forces acting on the object should be taken into account, and the appropriate equations should be used to calculate the work done and distance traveled. It is important to consider all factors and not make assumptions based on a single equation or value.