/*! 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 94 The potential energy of an objec... [FREE SOLUTION] | 91Ó°ÊÓ

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The potential energy of an object in the gravitational field of the earth is \(E_{p}=m g h .\) What must be the SI unit of \(g\) if this equation is to be consistent with the SI unit of energy for \(E_{p}\) ?

Short Answer

Expert verified
The SI unit of \(g\) is \(\text{m/s}^2\).

Step by step solution

01

Identify the SI Units for Each Variable

The potential energy \(E_p\) is given in the equation \(E_p = mgh\). We know that the SI unit for energy \(E_p\) is the Joule \(\text{J}\). The mass \(m\) has the SI unit of kilograms \(\text{kg}\), and height \(h\) is in meters \(\text{m}\). Our goal is to determine the unit for gravitational acceleration \(g\) that will make the units consistent.
02

Use Dimensional Analysis for consistency

Substituting SI units into the equation \(E_p = mgh\), we want to ensure that:\[ \text{[Energy]} = [m][g][h] \]In terms of units, this is:\[ \text{J} = \text{kg} \cdot [g] \cdot \text{m} \]We know that the Joule \(\text{J}\) is equivalent to \(\text{kg} \cdot \text{m}^2/\text{s}^2\).
03

Solve for the Unit of g

Now, equate the units:\[ \text{kg} \cdot \text{m}^2/\text{s}^2 = \text{kg} \cdot [g] \cdot \text{m} \]To solve for \( [g] \), cancel the \( \text{kg} \) on both sides and divide by \( \text{m} \):\[ [g] = \frac{\text{m}^2/\text{s}^2}{\text{m}} = \frac{\text{m}}{\text{s}^2} \]
04

Conclusion: Determine the Unit of g

Hence, the SI unit for \(g\) is derived to be meters per second squared \([g] = \text{m/s}^2\). This ensures the equation is dimensional consistent with energy in Joules.

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Key Concepts

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

Dimensional Analysis
Dimensional analysis is a systematic way to check the consistency of a physics equation. It involves verifying that all terms in an equation have the correct units, ensuring that both sides match in terms of their dimensions.
For gravitational potential energy, the equation is given by: \[ E_{p}=mgh \] Substituting known units, we have: - Energy \(E_p\) in Joules (\(\text{J}\)) - Mass \(m\) in kilograms (\(\text{kg}\)) - Height \(h\) in meters (\(\text{m}\))To do dimensional analysis, compare:\[ \text{[Energy]} = [m][g][h] \] with corresponding units: - \(\text{J} = \text{kg} \times [g] \times \text{m}\)This ensures every part of the equation is dimensionally consistent.
SI Units
SI units, short for the International System of Units, provide a standard for measuring physical quantities. This system ensures consistent communication of measurements worldwide. Some essential SI units in physics problem-solving include:- Mass: measured in kilograms (\(\text{kg}\))- Length: measured in meters (\(\text{m}\)) - Time: measured in seconds (\(\text{s}\))
When calculating gravitational potential energy, recognizing SI units is crucial to ensure dimensional accuracy. For energy, the Joule (\(\text{J}\)) is pivotal, defined as:\[ 1 \text{J} = 1 \text{kg} \times 1 \text{m}^2/\text{s}^2 \]Incorporating these consistent units allows us to solve equations with confidence.
Gravitational Acceleration
Gravitational acceleration \(g\) is a constant that appears in calculations involving gravity, like gravitational potential energy. Its value reflects how fast an object accelerates due to Earth's gravity, approximately \(9.81 \text{m/s}^2\) on Earth's surface.
When we analyzed the dimensions of the equation \(E_{p}=mgh\), it was critical to find \(g\)'s unit to ensure it reflects physical reality. By breaking down Joules and other terms: \[ \text{kg} \times \text{m}^2/\text{s}^2 = \text{kg} \times [g] \times \text{m}\] We derived that \( [g] = \text{m/s}^2\), maintaining consistency within the SI unit framework. Understanding \(g\)'s unit is important for applications involving motion and forces, solidifying its role in physics.
Physics Problem Solving
Successful physics problem-solving involves clear steps and rigorous thinking. First, identify what is given and what is asked. Consider the following steps when tackling problems:
  • Identify the given quantities and their units.
  • Choose the correct formula and express it in terms of variables with SI units.
  • Perform dimensional analysis to ensure all units match correctly.
  • Solve the equation step-by-step, ensuring clarity in each algebraic manipulation.
By approaching problems with this systematic methodology, students can break complex physics problems into manageable parts, minimizing errors and gaining deeper understanding. These practices are foundational for physics and facilitate insight into the subject's intricate beauty.

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Most popular questions from this chapter

The maximum mass allowed for a bowling ball in ten-pin bowling is 16 lb. The average speed of the ball when released during a game is between about 17 to 19 miles per hour (mph). Imagine that a 16.0 -lb bowling ball is flung up an incline at \(18.0 \mathrm{mph}\). The ball rolls up the incline, reaching a certain height \(h\) above where it started before rolling backward down the slope. What is the maximum height \(h\) (in meters) attained by the bowling ball? Neglect any loss of energy through friction with the incline or with air.

Ammonia will burn in the presence of a platinum catalyst to produce nitric oxide, NO. $$ 4 \mathrm{NH}_{3}(g)+5 \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_{2} \mathrm{O}(g) $$ What is the heat of reaction at constant pressure? Use the following thermochemical equations: $$ \begin{aligned} \mathrm{N}_{2}(g)+\mathrm{O}_{2}(g) & \longrightarrow 2 \mathrm{NO}(g) ; \Delta H=180.6 \mathrm{~kJ} \\ \mathrm{~N}_{2}(g)+3 \mathrm{H}_{2}(g) \longrightarrow 2 \mathrm{NH}_{3}(g) ; \Delta H &=-91.8 \mathrm{~kJ} \\ 2 \mathrm{H}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(g) ; \Delta H=-483.7 \mathrm{~kJ} \end{aligned} $$

An industrial process for manufacturing sulfuric acid, \(\mathrm{H}_{2} \mathrm{SO}_{4}\), uses hydrogen sulfide, \(\mathrm{H}_{2} \mathrm{~S}\), from the purification of natural gas. In the first step of this process, the hydrogen sulfide is burned to obtain sulfur dioxide, \(\mathrm{SO}_{2}\). $$ \begin{aligned} 2 \mathrm{H}_{2} \mathrm{~S}(g)+3 \mathrm{O}_{2}(g) & \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(l)+2 \mathrm{SO}_{2}(g) \\ \Delta H^{\circ}=-1124 \mathrm{~kJ} \end{aligned} \( The density of sulfur dioxide at \)25^{\circ} \mathrm{C}\( and \)1.00 \mathrm{~atm}\( is \)2.62 \mathrm{~g} / \mathrm{L},\( and the molar heat capacity is \)30.2 \mathrm{~J} /\left(\mathrm{mol} \cdot{ }^{\circ} \mathrm{C}\right)\( (a) How much heat would be evolved in producing \)1.00 \mathrm{~L}\( of \)\mathrm{SO}_{2}\( at \)25^{\circ} \mathrm{C}\( and \)1.00 \mathrm{~atm} ?\( (b) Suppose heat from this reaction is used to heat \)1.00 \mathrm{~L}\( of the \)\mathrm{SO}_{2}\( from \)25^{\circ} \mathrm{C}\( to \)500^{\circ} \mathrm{C}$ for its use in the next step of the process. What percentage of the heat evolved is required for this?

Define the heat capacity of a substance. Define the specific heat of a substance.

A sample of ethanol, \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\), weighing \(2.84 \mathrm{~g}\) was burned in an excess of oxygen in a bomb calorimeter. The temperature of the calorimeter rose from \(25.00^{\circ} \mathrm{C}\) to \(33.73^{\circ} \mathrm{C}\). If the heat capacity of the calorimeter and contents was \(9.63 \mathrm{~kJ} /{ }^{\circ} \mathrm{C}\), what is the value of \(q\) for burning \(1.00 \mathrm{~mol}\) of ethanol at constant volume and \(25.00^{\circ} \mathrm{C} ?\) The reaction is $$ \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(l)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g)+3 \mathrm{H}_{2} \mathrm{O}(l) $$ Is \(q\) equal to \(\Delta U\) or \(\Delta H\) ?

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