Solve Integrals and Work: 500 lb Bucket of Cement

In summary, the problem involves a worker on a scaffolding needing to lift a 500 lb bucket of cement from the ground to a point 30 ft above the ground using a 0.5 lb/ft rope. The solution involves separating the problem into two parts, with one part being constant and the other not. One way to solve it is by expressing the force as a function of distance above the ground and integrating it. Another approach is to imagine small sections of rope and summing their work, which can then be converted into an integral.
  • #1
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Homework Statement



A worker on a scaffolding 75 ft above the ground needs to lift a 500 lb bucket of cement from the ground to a point 30 ft above the ground by pulling on a rope weighing 0.5 lb/ft. How much work is required?


Homework Equations



W = F * D

The Attempt at a Solution



I know that I would have to separate the problem into two parts. The part with the bucket is constant, and the part with the chain is not constant because certain parts of the chain move up different distances than other parts. I'm not sure how to set everything up though.
 
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  • #2
First express F as a function of distance above the ground then integrate it. Hint: F is linear and F(0 feet)=515 lbs, F(30 feet)=500 lbs.
 
  • #3
Another way to do it: imagine a small section of rope of length, say [itex]\Delta x[/itex] at height x above the ground- small enough so the we can approximate the distance each point on that section has to be lifted by 30-x. It weighs [/itex]0.5\Delta x[/itex] pounds and must be lifted 30- x feet: the work done in lifting that section of rope is [itex]0.5(30- x)\Delta x[/itex] feet. Summing over all "small sections" for x= 0 to 30, gives a Riemann sum which can be converted into an integral.
 

1. What is an integral?

An integral is a mathematical concept that represents the accumulation or total of a changing quantity. It is often used to find the area under a curve on a graph.

2. How do you solve integrals?

Integrals can be solved using various methods such as substitution, integration by parts, or using specific formulas. The method used depends on the complexity of the integrand.

3. What is the work in the context of integrals?

In the context of integrals, work refers to the amount of energy required to move an object against a force. It is usually represented as the integral of the product of force and displacement.

4. How do you calculate the work required to lift a 500 lb bucket of cement?

To calculate the work required to lift a 500 lb bucket of cement, we need to know the height at which the bucket needs to be lifted. The work can then be calculated using the formula W = mgh, where m is the mass of the bucket, g is the acceleration due to gravity, and h is the height. We can also use the formula W = ∫F(x)dx, where F(x) is the force required to lift the bucket at a certain height x.

5. Can integrals be used in real-life scenarios?

Yes, integrals have various real-life applications such as calculating areas, volumes, and even work. They are commonly used in engineering, physics, and economics to solve problems involving changing quantities.

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