Question
Determine the work done by a person when lowering an object of mass 2.6 kg by a distance of 2.4 m. The person applies a force Fext such that the object moves with constant speed, i.e., without acceleration?
My ans:
W=F*d
F = ma
But it's saying constant speed so a=0
However, I realized Fext acts opposite to the weight of the object
so F=mg
and then I can use that value.
Is this correct? Or am I applying the wrong idea
My ans:
W=F*d
F = ma
But it's saying constant speed so a=0
However, I realized Fext acts opposite to the weight of the object
so F=mg
and then I can use that value.
Is this correct? Or am I applying the wrong idea
Answers
bobpursley
Work=mg*d and that is the energy the person absorbs. Work=mg*d is the work gravity does. Amazing, gravity does work on the person's arms, and he feels it.
Nikita
Ok I got -W
Because I used g=-9.8m/s^2 because it is acting in the opposite direction relative to the vertical y-axis.
Is this correct? What does -W mean though?
Because I used g=-9.8m/s^2 because it is acting in the opposite direction relative to the vertical y-axis.
Is this correct? What does -W mean though?