Pablo's Barbell Lift: When Does He Do Work?

When does Pablo do work on the barbell?

During which stage of the lift does Pablo do work on the barbell?

A) when he holds the barbell up above his head

B) when he applies force to the barbell but has not moved it

C) when he lifts the barbell from the floor to his chest

D) when he lets go of the barbell and allows it to fall to the ground

Answer:

The answer is: C) When he lifts the barbell from the floor to his chest.

Explanation:

The work is said to be done only when Pablo lifts the barbell from the floor to his chest.

What is Work Done?

The force applied to any object to displace it for some distance is known as work done. Conversely, the work is said to be done when the applied force tends to shift any object to some specific distance. The mathematical expression for the work done is given as,

W = F × s

Here, F is the applied force and s is the distance moved.

Now, when Pablo lifts a barbell, the work will only be said to be done when the barbell gets displaced from the floor. And as per the given options, the condition of displacement of the barbell from the floor to chest shows the actual case of work done.

Thus, we can conclude that the work is said to be done only when Pablo lifts the barbell from the floor to his chest.