College Physics: A Strategic Approach (3rd Edition)
College Physics: A Strategic Approach (3rd Edition)
3rd Edition
ISBN: 9780321879721
Author: Randall D. Knight (Professor Emeritus), Brian Jones, Stuart Field
Publisher: PEARSON
bartleby

Concept explainers

Textbook Question
Book Icon
Chapter P.3, Problem 3P

Size and Life

Physicists look for simple models and general principles that underlie and explain diverse physical phenomena. In the first 13 chapters of this textbook, you’ve seen that just a handful of general principles and laws can be used to solve a wide range of problems. Can this approach have any relevance to a subject like biology? It may seem surprising, but there are general 'laws of biology“’ that apply, with quantitative accuracy, to organisms as diverse as elephants and mice.

Let’s look at an example. An elephant uses more metabolic power than a mouse. This is not surprising, as an elephant is much bigger. But recasting the data shows an interesting trend. When we looked at the energy required to raise the temperature of different substances, we considered specific heat. The “specific” meant that we considered the heat required for 1 kilogram. For animals, rather than metabolic rate, we can look at the specific metabolic rate, the metabolic power used per kilogram of tissue. If we factor out the mass difference between a mouse and an elephant, are their specific metabolic powers the same?

In fact, the specific metabolic rate varies quite a bit among mammals, as the graph of specific metabolic rate versus mass shows. But there is an interesting trend: All of the data points lie on a single smooth curve. In other words, there really is a biological law we can use to predict a mammal’s metabolic rate knowing only its mass M. In particular, the specific metabolic rate is proportional to M –0.25. Because a 4000 kg elephant is 160,000 times more massive than a 25 g mouse, the mouse’s specific metabolic power is (160,000)0.25 = 20 times that of the elephant. A law that shows how a property scales with the size of a system is called a scaling law.

Chapter P.3, Problem 3P, Size and Life Physicists look for simple models and general principles that underlie and explain

A similar scaling law holds for birds, reptiles, and even bacteria. Why should a single simple relationship hold true for organisms that range in size from a single cell to a 100 ton blue whale? Interestingly, no one knows for sure. It is a matter of current research to find out just what this and other scaling laws tell us about the nature of life.

Perhaps the metabolic-power scaling law is a result of heat transfer. In Chapter 12, we noted that all metabolic energy used by an animal ends up as heat, which must be transferred to the environment. A 4000 kg elephant has 160,000 times the mass of a 25 g mouse, but it has only about 3000 times the surface area. The heat transferred to the environment depends on the surface area; the more surface area, the greater the rate of heat transfer. An elephant with a mouse-sized metabolism simply wouldn't be able to dissipate heat fast enough—it would quickly overheat and die.

If heat dissipation were the only factor limiting metabolism, we can show that the specific metabolic rate should scale as M–0.33quite different from the M–0.25 scaling observed. Clearly, another factor is at work. Exactly what underlies the M–0.25 scaling is still a matter of debate, but some recent analysis suggests the scaling is due to limitations not of heat transfer but of fluid flow. Cells in mice, elephants, and all mammals receive nutrients and oxygen for metabolism from the bloodstream. Because the minimum size of a capillary is about the same for all mammals, the structure of the circulatory system must vary from animal to animal. The human aorta has a diameter of about 1 inch; in a mouse, the diameter is approximately l/20th of this. Thus a mouse has fewer levels of branching to smaller and smaller blood vessels as we move from the aorta to the capillaries. The smaller blood vessels in mice mean that viscosity is more of a factor throughout the circulatory system. The circulatory system of a mouse is quite different from that of ail elephant.

A model of specific metabolic rate based on blood-flow limitations predicts a M–0.25 law, exactly as observed. The model also makes other testable predictions. For example, the model predicts that the smallest possible mammal should have a body mass of about 1 gram—exactly the size of the smallest shrew. Even smaller animals have different types of circulatory' systems; in the smallest animals, nutrient transport is by diffusion alone. But the model can be extended to predict that the specific metabolic rate for these animals will follow a scaling law similar to that for mammals, exactly as observed. It is too soon to know if this model will ultimately prove to be correct, but it’s indisputable that there are large-scale regularities in biology that follow mathematical relationships based on the laws of physics.

The following questions are related to the passage "Size and Life" on the previous page.

Given the data of the graph, approximately how much energy, in Calories, would a 200 g rat use during the course of a day?

  1. A. 10
  2. B. 20
  3. C. 100
  4. D. 200
Blurred answer
Students have asked these similar questions
One mole of Gold (Au) atom has a mass of 197 g. We know that the density of gold is 19.30 g/cm3 in room temperature. Using those numbers, answer the following questions: a) What is the mass of a single gold atom in kg? b) Assume that gold atoms sit in a perfect cubic crystal structure. Estimate the distance between two gold atoms in meters.   c) If we have a gold cube of 6 cm on each side, how many atoms can we fit along the edge of each side of the cube?  d) What would be the mass, in kilograms, of the gold cube we discussed in part (c) (measuring 6 cm on each side)?
For this problem, we want to estimate the answer, so our assumptions may be a little unrealistic. Suppose we want to estimate how much air we need to send to a space station, assuming we cannot recycle air. Suppose four astronauts are in a spherical space station. If each of them typically breathes about 500 cm³of air with each breathe, and take 15 breathes per minute (average resting value): a. What is the volume of air you would need in the space station if these four astronauts stayed for a full year? b. If the density of air is 1.25 kg/m³ and it costs (thanks to SpaceX) a mere $100/kg to send objects to the space station, how much money would the astronaut air supply cost?
This is the lab and It is not the writing assignment. please help me with this.  I appreciate it. Thank you! please don't reject it!!

Chapter P Solutions

College Physics: A Strategic Approach (3rd Edition)

Ch. P.1 - The drag force on an object moving in a liquid is...Ch. P.1 - Sticky Liquids BIO The drag force on an object...Ch. P.1 - The drag force on an object moving in a liquid is...Ch. P.1 - Pulling Out of a Dive Falcons are excellent fliers...Ch. P.1 - Pulling Out of a Dive Falcons are excellent fliers...Ch. P.1 - Pulling Out of a Dive Falcons are excellent fliers...Ch. P.1 - Bending Beams If you bend a rod down, it...Ch. P.1 - Bending Beams If you bend a rod down, it...Ch. P.1 - Bending Beams If you bend a rod down, it...Ch. P.1 - Additional Integrated Problems 20. You go to the...Ch. P.1 - If you stand on a scale at the equator, the scale...Ch. P.1 - Additional Integrated Problems Dolphins and other...Ch. P.2 - Prob. 1PCh. P.2 - Prob. 2PCh. P.2 - Prob. 3PCh. P.2 - Prob. 4PCh. P.2 - The following passages and associated questions...Ch. P.2 - The following passages and associated questions...Ch. P.2 - The following passages and associated questions...Ch. P.2 - The following passages and associated questions...Ch. P.2 - The following passages and associated questions...Ch. P.2 - Testing Tennis Balls Tennis balls are tested by...Ch. P.2 - Testing Tennis Balls Tennis balls are tested by...Ch. P.2 - Testing Tennis Balls Tennis balls are tested by...Ch. P.2 - Squid Propulsion Squid usually move by using their...Ch. P.2 - Squid Propulsion Squid usually move by using their...Ch. P.2 - Squid Propulsion Squid usually move by using their...Ch. P.2 - Squid Propulsion Squid usually move by using their...Ch. P.2 - Teeing Off A golf club has a lightweight flexible...Ch. P.2 - Teeing Off A golf club has a lightweight flexible...Ch. P.2 - Teeing Off A golf club has a lightweight flexible...Ch. P.2 - Teeing Off A golf club has a lightweight flexible...Ch. P.2 - Additional Integrated Problems Football players...Ch. P.2 - Additional Integrated Problems The unit of...Ch. P.2 - Additional Integrated Problems A 100 kg football...Ch. P.2 - Additional Integrated Problems A swift blow with...Ch. P.2 - Additional Integrated Problems A childs sled has...Ch. P.3 - Size and Life Physicists look for simple models...Ch. P.3 - Size and Life Physicists look for simple models...Ch. P.3 - Size and Life Physicists look for simple models...Ch. P.3 - Size and Life Physicists look for simple models...Ch. P.3 - Prob. 6PCh. P.3 - Prob. 7PCh. P.3 - Prob. 8PCh. P.3 - Prob. 9PCh. P.3 - Prob. 10PCh. P.3 - Prob. 11PCh. P.3 - Prob. 12PCh. P.3 - Prob. 13PCh. P.3 - Prob. 14PCh. P.3 - Passenger Balloons Long-distance balloon flights...Ch. P.3 - Passenger Balloons Long-distance balloon flights...Ch. P.3 - Passenger Balloons Long-distance balloon flights...Ch. P.3 - Prob. 18PCh. P.3 - Prob. 19PCh. P.3 - Prob. 20PCh. P.3 - Prob. 21PCh. P.4 - Waves in the Earth and the Ocean In December 2004,...Ch. P.4 - Waves in the Earth and the Ocean In December 2004,...Ch. P.4 - Waves in the Earth and the Ocean In December 2004,...Ch. P.4 - Waves in the Earth and the Ocean In December 2004,...Ch. P.4 - Waves in the Earth and the Ocean In December 2004,...Ch. P.4 - Prob. 6PCh. P.4 - Prob. 7PCh. P.4 - Prob. 8PCh. P.4 - Prob. 9PCh. P.4 - Prob. 10PCh. P.4 - Prob. 11PCh. P.4 - Prob. 12PCh. P.4 - Prob. 13PCh. P.4 - Prob. 14PCh. P.4 - Prob. 15PCh. P.4 - Prob. 16PCh. P.4 - In the Swing A rope swing is hung from a tree...Ch. P.4 - In the Swing A rope swing is hung from a tree...Ch. P.4 - In the Swing A rope swing is hung from a tree...Ch. P.4 - Additional Integrated Problems The jumping gait of...Ch. P.4 - Prob. 21PCh. P.5 - Scanning Confocal Microscopy Although modern...Ch. P.5 - If, because of a poor-quality objective, the light...Ch. P.5 - The resolution of a scanning confocal microscope...Ch. P.5 - Prob. 4PCh. P.5 - In a horses eye, the image of a close object will...Ch. P.5 - Prob. 6PCh. P.5 - A horse is looking straight ahead at a person who...Ch. P.5 - Prob. 8PCh. P.5 - Light of wavelength 600 nm in air passes into the...Ch. P.5 - Prob. 10PCh. P.5 - Prob. 11PCh. P.5 - 12. In human vision, the curvature of the cornea...Ch. P.5 - Prob. 13PCh. P.5 - 14. Figure V.2c shows the lens of the eye bringing...Ch. P.5 - The pupil of your eye is smaller in bright light...Ch. P.5 - People with good vision can make out an...Ch. P.5 - Prob. 17PCh. P.5 - Prob. 18PCh. P.6 - The Greenhouse Effect and Global Warming...Ch. P.6 - The Greenhouse Effect and Global Warming...Ch. P.6 - The Greenhouse Effect and Global Warming...Ch. P.6 - The Greenhouse Effect and Global Warming...Ch. P.6 - The Greenhouse Effect and Global Warming...Ch. P.6 - Prob. 6PCh. P.6 - Prob. 7PCh. P.6 - The following passages and associated questions...Ch. P.6 - Prob. 9PCh. P.6 - Prob. 10PCh. P.6 - Prob. 11PCh. P.6 - Electric Cars In recent years, practical hybrid...Ch. P.6 - Electric Cars In recent years, practical hybrid...Ch. P.6 - Electric Cars In recent years, practical hybrid...Ch. P.6 - Electric Cars In recent years, practical hybrid...Ch. P.6 - Wireless Power Transmission Your laptop has...Ch. P.6 - Wireless Power Transmission Your laptop has...Ch. P.6 - Wireless Power Transmission Your laptop has...Ch. P.6 - Wireless Power Transmission Your laptop has...Ch. P.6 - Additional Integrated Problems 20. A 20 resistor...Ch. P.6 - Prob. 21PCh. P.7 - Prob. 1PCh. P.7 - Prob. 2PCh. P.7 - Prob. 3PCh. P.7 - Prob. 4PCh. P.7 - Prob. 5PCh. P.7 - Prob. 6PCh. P.7 - Prob. 7PCh. P.7 - Prob. 8PCh. P.7 - Prob. 9PCh. P.7 - Prob. 10PCh. P.7 - Prob. 11PCh. P.7 - Prob. 12PCh. P.7 - Prob. 13PCh. P.7 - Prob. 14PCh. P.7 - Prob. 15PCh. P.7 - Prob. 16PCh. P.7 - Prob. 17PCh. P.7 - Prob. 18PCh. P.7 - Many speculative plans for spaceships capable of...Ch. P.7 - A muon is a lepton that is a higher-mass (rest...Ch. P.7 - A muon is a lepton that is a higher-mass (rest...
Knowledge Booster
Background pattern image
Physics
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
University Physics Volume 1
Physics
ISBN:9781938168277
Author:William Moebs, Samuel J. Ling, Jeff Sanny
Publisher:OpenStax - Rice University
Text book image
Physics for Scientists and Engineers: Foundations...
Physics
ISBN:9781133939146
Author:Katz, Debora M.
Publisher:Cengage Learning
Text book image
Physics for Scientists and Engineers, Technology ...
Physics
ISBN:9781305116399
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning