Textbook Question
Bacteria vary in size, but a diameter of 2.0 μm is not unusual. What are the volume (in cubic centimeters) and surface area (in square millimeters) of a spherical bacterium of that size?
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Ch 01: Units, Physical Quantities & Vectors
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610
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Table of contents
- Ch 01: Units, Physical Quantities & Vectors41
- Ch 02: Motion Along a Straight Line67
- Ch 03: Motion in Two or Three Dimensions47
- Ch 04: Newton's Laws of Motion23
- Ch 05: Applying Newton's Laws59
- Ch 06: Work & Kinetic Energy14
- Ch 07: Potential Energy & Conservation8
- Ch 08: Momentum, Impulse, and Collisions18
- Ch 09: Rotation of Rigid Bodies42
- Ch 10: Dynamics of Rotational Motion48
- Ch 11: Equilibrium & Elasticity27
- Ch 12: Fluid Mechanics31
- Ch 13: Gravitation35
- Ch 14: Periodic Motion32
- Ch 15: Mechanical Waves25
- Ch 16: Sound & Hearing32
- Ch 17: Temperature and Heat36
- Ch 18: Thermal Properties of Matter38
- Ch 19: The First Law of Thermodynamics33
- Ch 20: The Second Law of Thermodynamics22
- Ch 21: Electric Charge and Electric Field36
- Ch 22: Gauss' Law24
- Ch 23: Electric Potential31
- Ch 24: Capacitance and Dielectrics18
- Ch 25: Current, Resistance, and EMF26
- Ch 26: Direct-Current Circuits30
- Ch 27: Magnetic Field and Magnetic Forces18
- Ch 28: Sources of Magnetic Field10
- Ch 29: Electromagnetic Induction28
- Ch 30: Inductance17
- Ch 31: Alternating Current21
- Ch 32: Electromagnetic Waves1
- Ch 33: The Nature and Propagation of Light20
- Ch 34: Geometric Optics34
- Ch 35: Interference19
- Ch 36: Diffraction25
- Ch 37: Special Relativity20
- Ch 38: Photons: Light Waves Behaving as Particles15
- Ch 39: Particles Behaving as Waves26
- Ch 40: Quantum Mechanics I: Wave Functions21
- Ch 41: Quantum Mechanics II: Atomic Structure25
- Ch 42: Molecules and Condensed Matter18
- Ch 43: Nuclear Physics16
- Ch 44: Particle Physics and Cosmology23
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Not the one you use?Change textbook
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Young & Freedman Calc 14th EditionCh 01: Units, Physical Quantities & VectorsProblem 12d
Young & Freedman Calc 14th EditionCh 01: Units, Physical Quantities & VectorsProblem 12dChapter 1, Problem 12d
The RDA for the trace element selenium is 0.000070 g/day. Express this dose in mg/day.
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Understand the relationship between grams and milligrams. There are 1000 milligrams in 1 gram.
Identify the given value in grams, which is 0.000070 g/day.
To convert grams to milligrams, multiply the given value by 1000. This is because 1 gram is equal to 1000 milligrams.
Set up the conversion equation: \( \text{milligrams/day} = \text{grams/day} \times 1000 \).
Substitute the given value into the equation: \( \text{milligrams/day} = 0.000070 \times 1000 \).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Unit Conversion
Unit conversion is the process of converting a quantity expressed in one unit to another unit. In this case, converting grams to milligrams involves multiplying the given value by 1,000, since 1 gram equals 1,000 milligrams. This is essential for expressing the recommended daily allowance (RDA) of selenium in the desired unit.
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Trace Elements
Trace elements are minerals required by the body in very small amounts for various physiological functions. Selenium is one such trace element, important for antioxidant protection and thyroid function. Understanding the significance of trace elements helps in appreciating why precise dosages, like the RDA, are crucial for health.
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Recommended Dietary Allowance (RDA)
The Recommended Dietary Allowance (RDA) is the average daily intake level of a nutrient considered sufficient to meet the requirements of most healthy individuals. It is a guideline used to ensure adequate nutrition and prevent deficiencies. Knowing the RDA helps in understanding the importance of the specified dose of selenium for maintaining health.
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Related Practice
Textbook Question
A certain fuel-efficient hybrid car gets gasoline mileage of 55.0 mpg (miles per gallon). If you are driving this car in Europe and want to compare its mileage with that of other European cars, express this mileage in km/L (L = liter).
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Textbook Question
While driving in an exotic foreign land, you see a speed limit sign that reads 180,000 furlongs per fortnight. How many miles per hour is this?
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Textbook Question
With a wooden ruler, you measure the length of a rectangular piece of sheet metal to be 12 mm. With micrometer calipers, you measure the width of the rectangle to be 5.98 mm. Use the correct number of significant figures: What is the area of the rectangle?
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Textbook Question
With a wooden ruler, you measure the length of a rectangular piece of sheet metal to be 12 mm. With micrometer calipers, you measure the width of the rectangle to be 5.98 mm. Use the correct number of significant figures: What is the perimeter of the rectangle?
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Textbook Question
In the fall of 2002, scientists at Los Alamos National Laboratory determined that the critical mass of neptunium-237 is about 60 kg. The critical mass of a fissionable material is the minimum amount that must be brought together to start a nuclear chain reaction. Neptunium-237 has a density of 19.5 g/cm3. What would be the radius of a sphere of this material that has a critical mass?
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