Physics Mechanics and Energy Concepts
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Questions and Answers

What does the variable VP represent in the equations provided?

  • Viscous Pressure
  • Velocity Pressure (correct)
  • Variable Pressure
  • Volume Pressure

In the formula for concentration C, what does Pb stand for?

  • Barometric pressure (correct)
  • Boiling pressure
  • Partial pressure of a gas
  • Base pressure

Which formula accurately represents the relationship of Total Pressure (TP)?

  • TP = SP * VP
  • TP = SP - VP
  • TP = VP - SP
  • TP = SP + VP (correct)

What does the variable SG represent in the equation for ventilation rate Q?

<p>Specific Gravity (B)</p> Signup and view all the answers

Which equation is used to calculate the coefficient of entry loss (Ce)?

<p>Ce = VP / SPh (D)</p> Signup and view all the answers

What does the variable G represent in the contamination generation formula?

<p>Generation rate (C)</p> Signup and view all the answers

Which variable represents the desired concentration of gas or vapor in the ventilation equation for Q?

<p>C (B)</p> Signup and view all the answers

In the formula for future value, which variable stands for the present value?

<p>P (C)</p> Signup and view all the answers

What does the equation 'R(t) = e^{- ext{λ}t}' represent?

<p>Reliability function (C)</p> Signup and view all the answers

In the formula for sound intensity I, what does the variable ρ represent?

<p>Density of the medium (C)</p> Signup and view all the answers

What does Lpt represent in sound intensity calculations?

<p>Combined sound pressure level (A)</p> Signup and view all the answers

In the equation for sound power level, which variable represents the reference acoustic power?

<p>Wo (D)</p> Signup and view all the answers

How is the dosage (D) calculated in relation to actual exposure time and allowed exposure time?

<p>D = 100 ∑(Ci / Ti) (C)</p> Signup and view all the answers

What does the term 'TWA' signify in exposure calculations?

<p>Time weighted average (D)</p> Signup and view all the answers

In the sound level distance calculation, what does 'dBo' denote?

<p>The original sound level measurement (A)</p> Signup and view all the answers

Which formula relates the intensity of sound at different distances from its source?

<p>I2 = I1 * (d1^2 / d2^2) (A)</p> Signup and view all the answers

In noise reduction (NR) calculations, what does 'A1' represent?

<p>Total number of absorption units before treatment (A)</p> Signup and view all the answers

What does the variable 'α' indicate in relation to noise reduction?

<p>Absorption coefficient of the lining material (C)</p> Signup and view all the answers

In the formula for calculating power density (W), which element correlates directly with antenna power?

<p>P (B)</p> Signup and view all the answers

What does 'β' factor represent in the intensity calculations regarding radiation?

<p>Radiation scatter buildup factor (C)</p> Signup and view all the answers

What does the symbol 'μ' represent in the equation F = μN?

<p>Coefficient of friction (A)</p> Signup and view all the answers

Using the equation v = vo + at, what will be the velocity (v) of an object that starts from rest (vo = 0) after 5 seconds if the acceleration (a) is 2 m/s²?

<p>10 m/s (D)</p> Signup and view all the answers

In the equation for kinetic energy K.E. = mv²/2, which variable directly affects the kinetic energy the most?

<p>Speed of the object (B)</p> Signup and view all the answers

Which of the following expressions correctly represents the conservation of energy principle using potential energy (P.E.) and kinetic energy (K.E.)?

<p>P.E. + K.E. = constant (B)</p> Signup and view all the answers

If the height (h) in the potential energy equation P.E. = mgh is doubled, how does it affect the potential energy, assuming mass (m) and gravitational acceleration (g) remain constant?

<p>It doubles (A)</p> Signup and view all the answers

What units are used to measure frictional force (F) in the equation F = μN?

<p>Newtons (C)</p> Signup and view all the answers

What is the displacement (s) of an object if its initial velocity (vo) is 3 m/s, acceleration (a) is 2 m/s², and the time (t) is 4 seconds?

<p>30 meters (D)</p> Signup and view all the answers

Which of the following statements about the force balance in the equation F1D1 = F2D2 is true?

<p>It relates force and distance in a lever system (A)</p> Signup and view all the answers

If an object with a mass of 5 kg is raised to a height of 10 meters, what is its potential energy (P.E.)?

<p>98 Joules (D)</p> Signup and view all the answers

Which of the following equations is correctly arranged to find the final velocity (v) when initial velocity (vo) is known?

<p>$v = v_o + at$ (C)</p> Signup and view all the answers

What does the constant $24.45$ represent in the formula for calculating parts per million (ppm)?

<p>The volume in liters of one mole of gas (C)</p> Signup and view all the answers

What is the formula for the recommended weight limit (RWL) in the ergonomic lifting index calculation?

<p>RWL = LC × HM × VM × DM × AM × FM × CM (A)</p> Signup and view all the answers

In the equation $W = Fs$, what happens to the amount of work done if the force is doubled while maintaining the distance constant?

<p>The work done is doubled (A)</p> Signup and view all the answers

What is the correct relationship of pressure, volume, and temperature in the ideal gas law?

<p>PV = nRT (A)</p> Signup and view all the answers

Which formula defines the lifting index (LI) in ergonomic lifting calculations?

<p>LI = L / RWL (B)</p> Signup and view all the answers

What does the variable 'g' represent in the work equation $W = mg$?

<p>Acceleration due to gravity (A)</p> Signup and view all the answers

In the context of static pressure, what does SPfan represent?

<p>Static pressure at the output minus the static pressure at the input (C)</p> Signup and view all the answers

Which of the following is true regarding the formula for determining the static pressure of a hood (SPh)?

<p>SPh is always the absolute value of the calculated result (C)</p> Signup and view all the answers

What does 'F' represent in Newton's second law of motion as defined by the equation $F = ma$?

<p>Force in newtons (A)</p> Signup and view all the answers

In calculating TLVm for a mixture of chemicals, what do the TLV values represent?

<p>Concentration limits for each individual chemical (D)</p> Signup and view all the answers

Flashcards

Frictional Force

The force resisting motion between two surfaces in contact.

Coefficient of Friction (μ)

A measure of the roughness of two surfaces in contact. A higher coefficient means greater friction.

Normal Force (N)

The force acting perpendicular to the surface of an object.

Work (W)

The product of force and distance travelled in the direction of force.

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Kinetic Energy (K.E.)

The energy possessed by an object due to its motion.

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Potential Energy (P.E.)

The energy possessed by an object due to its position in a gravitational field.

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Acceleration (a)

The rate of change of velocity.

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Displacement (s)

The distance an object travels in a specific direction.

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Velocity (v)

The speed of an object in a specific direction.

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Initial Velocity (vo)

The initial velocity of an object at the start of its motion.

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Elastic Potential Energy

The energy stored in a spring due to its compression or extension. It's measured in Joules (J).

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Spring Constant (k)

The force required to extend or compress a spring by one unit of length. Measured in Newtons per meter (N/m).

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Compression/Extension (x)

The amount of compression or extension of a spring from its rest position. Measured in meters (m).

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Momentum (ρ)

A measure of an object's motion, calculated as mass multiplied by velocity. It's measured in kilogram meters per second (kg m/s).

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Force (F)

The product of an object's mass and acceleration. Measured in Newtons (N).

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Work Done by Gravity (W)

The work done on an object due to gravity. It's measured in Joules (J).

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Lifting Index (LI)

A measure of the safety of a lifting task. It's calculated as the ratio of the actual weight lifted to the recommended weight limit.

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Recommended Weight Limit (RWL)

The maximum recommended weight that should be lifted in a particular task. It's calculated based on factors like load, distance, and frequency.

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Parts per Million (ppm)

A measure of the concentration of a gas or vapor in air. Measured in parts per million (ppm).

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Hood Entry Loss (he)

Hood entry loss is the pressure drop that occurs when air enters a hood due to the resistance of the hood opening. It is measured in inches of water gauge (″wg).

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Coefficient of Entry Loss (Ce)

The coefficient of entry loss (Ce) is a dimensionless factor that represents the amount of pressure drop that occurs when air enters a hood. It is determined by the hood's geometry and the velocity of the air entering the hood.

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Velocity Pressure (VP)

Velocity pressure (VP) is the kinetic energy of the air moving within a duct. It is measured in inches of water gauge (″wg).

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Actual Ventilation Rate (Q)

The actual ventilation rate (Q) is the volume of air that is moved through a system per unit time. It is measured in cubic feet per minute (cfm).

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Specific Gravity (SG)

Specific gravity (SG) is the ratio of the density of a substance to the density of a reference substance. It is a dimensionless number.

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Evaporation Rate (ER)

Evaporation rate (ER) is the rate at which a liquid evaporates. It is measured in pints per minute.

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Design Distribution Constant (K)

The design distribution constant (K) is a factor that accounts for the incomplete mixing of contaminant air in a space. It has a range of 1 to 10.

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Molecular Weight (MW)

Molecular weight (MW) is the mass of a molecule of a substance relative to the mass of an atom of carbon-12. It is measured in g/mol.

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Concentration (C)

The concentration (C) of a substance in air is the amount of the substance present per unit volume of air. It is measured in parts per million (ppm).

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Total Pressure (TP)

Total pressure (TP) is the sum of static pressure (SP) and velocity pressure (VP). It is measured in inches of water gauge (″wg).

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Combined Sound Pressure Level (Lpt)

A combined measure of multiple individual sound pressure levels, often used to represent the overall noise level in a complex environment.

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Sound pressure level (Lp)

A measure of the sound intensity at a specific location, typically expressed in decibels (dB). It's affected by both the sound source and the distance from the source.

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Sound Power Level (Lw)

A measure of a sound source's overall power output, expressed in decibels (dB). It is intrinsic to the source and doesn't depend on the distance.

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Dosage Equation (D)

A formula used to calculate effective sound exposure over a period of time.

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Time Allowed for Exposure (T)

The amount of time a person can safely be exposed to a particular sound level. It varies depending on the intensity of the sound.

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Time Weighted Average (TWA)

A weighted average of noise levels over time, representing a person's overall exposure. Often used in workplace noise assessments.

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Distance Correction Equation

A calculation used to adjust a sound level measurement to account for the distance from the source.

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Absorption Units (Sabins)

A measure of the sound absorption within a room, expressed in Sabins. Higher absorption means less reflection and a quieter environment.

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Noise Reduction (NR)

A method for estimating noise reduction achieved by adding sound-absorbing material in a duct.

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Inverse Square Law for Radiation

A calculation used to determine the intensity of radiation at different distances from a source, based on the inverse square law.

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Study Notes

Mechanics

  • Frictional Force (F): Frictional force is measured in newtons and calculated as F = μN, where μ is the coefficient of friction and N represents Newtons.
  • Force (F): Force is measured in newtons.
  • Distance (D): Distance is a measure of length.
  • Velocity (v): Velocity is calculated as v = v° + at, where v° represents the original velocity, a is the acceleration, and t is time.
  • Acceleration (a): Acceleration is calculated using the appropriate formula.
  • Displacement (s): Displacement is the change in position of an object.
  • Final Velocity (v): This is determined by v² = v² + 2as, considering initial velocity (v), acceleration (a), and displacement or distance covered (s).

Energy

  • Kinetic Energy (K.E.): Kinetic energy (K.E.) is calculated as K.E. = 1/2mv², calculated from the mass (m) of the object and its speed or velocity (v).
  • Potential Energy (P.E.): Potential energy is measured in joules and calculated as P.E. = mgh. Variables include the mass (m) of the object, acceleration due to gravity (g), and height (h) above a reference surface.
  • Potential Energy (Elastic P.E.): Elastic potential energy is calculated as P.E. = 1/2kx², using the spring constant (k) and the amount of compression (x).

Momentum & Force

  • Momentum (p): Momentum (p) is determined by the product of mass (m) and velocity (v). p = mv
  • Force (F): Force (F) is determined by the product of mass (m) and acceleration (a). F = ma
  • Work Done by Gravity (W): Work done by gravity equals mg where m is the mass of the object and g is the acceleration due to gravity.

Ergonomics (NIOSH Lifting Equations)

  • Lifting Index (LI): The LI is calculated as LI = L/RWL, where L is the weight of the object and RWL is the recommended weight limit.
  • Recommended Weight Limit (RWL): This is calculated using various multipliers (horizontal, vertical, distance, asymmetric, frequency, and coupling).

Heat Stress & Relative Humidity

  • Indoor Heat Calculation: 0.7 WB + 0.3 GT where WB is wet-bulb temperature, and GT is globe temperature, as well as Indoor Calculation which involves no solar load.

Concentrations of Vapors and Gases

  • Parts per million (ppm): ppm is a unit of concentration, converting to mg/m³ using MW and the constant 24.45.
  • Threshold Limit Value (TLV): TLV is a limit value for a chemical's concentration in the air, relevant to different fractions (weight percent).

Ventilation

  • Volumetric Flow Rate (Q): Volumetric flow rate (Q) is calculated from velocity (V) and cross-sectional area (A) using Q = VA.
  • Velocity (V): Velocity (V) is calculated using 4005 √SPh.
  • Static Pressure (SP): Includes factors of duct velocity pressure (VP) and an entry loss term (h), where SP = VP + he .

Noise

  • Sound Intensity (I): Sound intensity (I) is equal to p²/(ρc), calculated from sound pressure level (p), the medium's density (ρ), and the speed of sound (c).
  • Combined Sound Pressure Level (Lpt): This combines individual measured sound pressure levels (Lpi).
  • Sound Power Level (Lw): Sound power level (Lw), is measured in decibels (dB) and calculated by 10log₁₀(W⁄W').

Reliability

  • Probability of Failure (P₁): Probability of failure is determined by P₁ = 1 – R(t) where R is reliability.
  • Reliability (R(t)): Reliability is calculated as R(t) = e⁻λt where t represents the time and λ represents the failure rate.

Radiation

  • Intensity (I): Intensity, calculated by the ratio of intensities I₂ / I₁=(d₁/d₂)²
  • Linear Attenuation Coefficient (μ): Relevant to calculating intensity through shielding or materials.

Engineering Economy

  • Future Value (F): Future value (F) of an investment is described by F = P(1 + i)ⁿ where P is the present value, i is interest rate in decimal, and n is the number of periods.
  • Present Value (P): Present value (P) of a future value (F) is given by P = F/(1 + i)ⁿ

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Description

Test your understanding of fundamental concepts in mechanics and energy, including frictional force, velocity, acceleration, kinetic and potential energy. This quiz covers essential formulas and definitions to help you grasp the basics of physics more effectively.

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