A person pulls a bucket of water up from a well with a rope. Assume the initial

Question

A person pulls a bucket of water up from a well with a rope. Assume the initial and final speeds of the bucket are zero (vi=vf=0), and that the person lifted the bucket a vertical distance h. By looking at energy changes in the bucket-Earth physical system, we can make sense of the force the person must exert to pull the bucket up and the amount of work the person does. a) Think about whether this is an open or closed system. What energy systems undergo a change in energy during the process? Construct a particular energy-system diagram for this process and include the algebraic expression of energy conservation (in terms of E’s and if open, any Heat or Work).

Explanation / Answer

This is a Closed system in terms of energy over here.

Look at the initial and ending energy states:

Initial energy of the bucket and water = 0

Final energy of the bucket and water = Potential energy = mass*height*g = massOfBucketWater*h*9.81 N/kg

That increase in energy is the amount of work done by the person (Wp).

Infact average force can also be calculated as follows:

Work = F*distance

Wp = Favg*height

=>   Favg = Wp/h = massofBucketWater*9.81 N/kg or rather simply, the weight of the bucket.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.