/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 74 A pump is required to lift 750 l... [FREE SOLUTION] | 91Ó°ÊÓ

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A pump is required to lift 750 liters of water per minute from a well \(14.0 \mathrm{~m}\) deep and eject it with a speed of \(18.0 \mathrm{~m} / \mathrm{s}\). How much work per minute does the pump do?

Short Answer

Expert verified
The pump does 224,505 Joules of work per minute.

Step by step solution

01

Convert Volume to Mass

First, convert the volume of water being pumped per minute (750 liters) into mass. Since 1 liter of water has a mass of 1 kg, 750 liters of water has a mass of 750 kg.
02

Calculate Gravitational Work

Calculate the work done in lifting the water against gravity. The formula for gravitational work is given by \[ W_g = mgh \]where \( m \) is the mass (750 kg), \( g \) is the acceleration due to gravity (9.81 m/s²), and \( h \) is the height (14 m). Substituting these values, we have:\[ W_g = 750 \times 9.81 \times 14 = 103005 \, \text{Joules} \]
03

Calculate Kinetic Energy Work

Calculate the work done to give the water kinetic energy using the formula:\[ W_k = \frac{1}{2}mv^2 \]where \( m \) is the mass (750 kg) and \( v \) is the ejected speed (18 m/s). Substituting these values, we have:\[ W_k = \frac{1}{2} \times 750 \times (18)^2 = 121500 \, \text{Joules} \]
04

Calculate Total Work per Minute

Add the work done against gravity and the work done for the kinetic energy to find the total work done by the pump per minute:\[ W_{\text{total}} = W_g + W_k = 103005 + 121500 = 224505 \, \text{Joules} \]

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Kinetic energy
Kinetic energy is the energy possessed by an object due to its motion. Determining kinetic energy is vital when analyzing objects in motion, such as the water in our pump exercise. To calculate it, we use the formula:\[ W_k = \frac{1}{2} mv^2 \]where:- \( m \) represents mass,- \( v \) stands for velocity.Substituting the known values of mass and velocity into this formula gave us a kinetic energy work of 121,500 Joules. Understanding kinetic energy helps explain how much energy is needed to propel the water at a given speed. It underscores how motion impacts energy needs, making it crucial in physics problem solving.
Gravitational work
Gravitational work refers to the energy required to move an object against gravity. It is particularly relevant when lifting objects, such as water in a pump scenario. The formula for calculating gravitational work is:\[ W_g = mgh \]where:- \( m \) is mass,- \( g \) is the acceleration due to gravity (9.81 m/s²),- \( h \) is the height the object is lifted.In our problem, by plugging in the figures for the mass of water, the gravitational acceleration, and the height, we got 103,005 Joules. Gravitational work is essential for understanding energy exchanges in systems where lifting or height change is involved.
Work-energy principle
The work-energy principle is a fundamental concept in physics that connects the work done by all forces acting on an object and the change in its kinetic energy. This principle emphasizes that the total work done on an object is the sum of its kinetic and potential energy changes.In our pump scenario, we calculated two types of work: the gravitational work needed to lift water and the kinetic work needed to move the water at a certain speed. Adding these gives the total work done by the pump:\[ W_{\text{total}} = W_g + W_k \]This principle helps us understand how energy transformations occur and allows students to predict how objects behave when acted upon by different forces.
Units conversion
Units conversion is crucial in solving physics problems because it ensures that our calculations stay consistent and meaningful. In this exercise, we started by converting volume from liters to mass in kilograms because physics problems often deal with mass instead of volume. Converting units is a straightforward but essential step, as it provides a common ground for calculations. Using the conversion rate that 1 liter of water equals 1 kilogram allowed us to determine the total mass of the water pumped, which was pivotal in further calculating work and energy. Mastering units conversion simplifies complex physics problem solving, ensuring that results are accurate and understandable.

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Most popular questions from this chapter

A force of magnitude \(800.0 \mathrm{~N}\) stretches a certain spring by \(0.200 \mathrm{~m}\) from its equilibrium position. (a) What is the force constant of this spring? (b) How much elastic potential energy is stored in the spring when it is: (i) stretched \(0.300 \mathrm{~m}\) from its equilibrium position and(ii) compressed by \(0.300 \mathrm{~m}\) from its equilibrium position? (c) How much work was done in stretching the spring by the original \(0.200 \mathrm{~m} ?\)

A \(12.0 \mathrm{~N}\) package of whole wheat flour is suddenly placed on the pan of a scale such as you find in grocery stores. The pan is supported from below by a vertical spring of force constant \(325 \mathrm{~N} / \mathrm{m}\). If the pan has negligible weight, find the maximum distance the spring will be compressed if no energy is dissipated by friction.

A bullet is fired into a large stationary absorber and comes to rest. Temperature measurements of the absorber show that the bullet lost \(1960 \mathrm{~J}\) of kinetic energy, and high-speed photos of the bullet show that it was moving at \(965 \mathrm{~m} / \mathrm{s}\) just as it struck the absorber. What is the mass of the bullet?

A factory worker moves a \(30.0 \mathrm{~kg}\) crate a distance of \(4.5 \mathrm{~m}\) along a level floor at constant velocity by pushing horizontally on it. The coefficient of kinetic friction between the crate and the floor is 0.25 . (a) What magnitude of force must the worker apply? (b) How much work is done on the crate by the worker's push? (c) How much work is done on the crate by friction? (d) How much work is done by the normal force? By gravity? (e) What is the net work done on the crate?

A \(68 \mathrm{~kg}\) skier approaches the foot of a hill with a speed of \(15 \mathrm{~m} / \mathrm{s}\). The surface of this hill slopes up at \(40.0^{\circ}\) above the horizontal and has coefficients of static and kinetic friction of 0.75 and \(0.25,\) respectively, with the skis. (a) Use energy conservation to find the maximum height above the foot of the hill that the skier will reach. (b) Will the skier remain at rest once she stops, or will she begin to slide down the hill? Prove your answer.

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