Work Done on 500N Barbell 0.5m Above Floor

In summary, The amount of work done on the barbell by holding it at a height of 0.5m for 100s is 0J. The equation W = Fdcos(phi) is used to calculate the work done, where F is the force applied (500N), d is the displacement (0.5m), and cos(phi) is the angle between the force and the displacement. In this case, cos(phi) is 0 because the force and displacement are in the same direction, resulting in 0J of work done.
  • #1
Dalip Saini
16
0

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.
 
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  • #2
Dalip Saini said:
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?
 
  • #3
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
 
  • #4
Dalip Saini said:
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?
 
  • #5
the displacement?
 
  • #6
Dalip Saini said:
the displacement?
Displacement of what?
 

FAQ: Work Done on 500N Barbell 0.5m Above Floor

How is work defined in physics?

Work is defined as the force applied on an object multiplied by the distance the object moves in the direction of the force. It is measured in joules (J).

What is the formula for calculating work?

The formula for calculating work is W = F * d, where W is the work done, F is the force applied, and d is the distance moved in the direction of the force.

How much work is done on a 500N barbell lifted 0.5m above the floor?

The work done on the barbell can be calculated by multiplying the force of 500N by the distance of 0.5m, which results in 250 joules (J).

Why is the height of the barbell above the floor important in determining the work done?

The height of the object above the ground is important because it affects the potential energy of the object. The work done is equal to the change in potential energy, which is determined by the height the object is lifted.

Can work be negative?

Yes, work can be negative if the force and the displacement are in opposite directions. This means that the object is moving in the direction opposite to the force applied on it, resulting in a negative work value.

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