Work Done on 500N Barbell 0.5m Above Floor

[Dalip Saini]

Homework Statement

You hold a 500N barbell 0.5m above a level floor for 100s . During this time, the amount of work you do on the barbell is

• 
  
  A
  
  1000J
• 
  
  B
  
  0J
• 
  
  C
  
  500J
• 
  
  D
  
  50000J

Homework Equations

W = Fdcos(phi)

The Attempt at a Solution

F= 500 N
d = 0.5 m
Since the difference in the vector direction is 0, I thought that all you had to do 500*0.5 = 250 J because cos(0) equals 1. But the answer is zero and I don't understand why.

 

[haruspex]

W = Fdcos(phi)

Equations aren't much use unless you know what all the variables in it represent.
What is d in this equation? Yes, I know it's a distance, but what distance in relation to F, exactly?

 

[Dalip Saini]

Its the distance of the barbell above the ground. So is that vector pointing down and the force is pointing up? But still cos(180) is still -1 not 0

 

[haruspex]

Its the distance of the barbell above the ground.

That's not what I asked.
Forget this specific problem for the moment. You quoted a standard equation. How is d defined in that equation?

 

[Dalip Saini]

the displacement?

 

[haruspex]

the displacement?

Displacement of what?