Rating: 
Summary: A Little Fast a Little Slow
Review: What Einstein Told His Barber by Robert L. Wolke This book is imaginative and entertaining. It explains in simple terms the hows and whys
of many things we observe often but really don't understand. His editor has done a fine job with spelling and punctuation, but he needs
someone to check his math: p13 "In one experiment, out of 500 .30-caliber machine-gun bullets fired
straight upward, only four landed within 10 square feet
(3 square meters) of the gun". While 10 feet is about 3 meters, 10 square feet is about 1 square meter and would
lie within 22 inches of the gun - not a very safe place to wait.
p26-27 "There is a certain speed called the ESCAPE VELOCITY, 25000 mph,
that an object must achieve to circle the Earth in stable orbit and
not fall down."
Actually the speed needed for circular orbit is less by a factor of
the square root of two, about 18000 mph. On p.121 the author has
astronauts orbiting at the proper speed.
Escape velocity launches an object into a parabolic trajectory which
Escapes (imagine that) the earths gravity and never returns. p33 (and p.64) Speed of light 186,000 miles per second (3 million kilometers per second) Oops! That should be 300,000 kilometers per second. p81 Author computes 621 degrees Fahrenheit to be twice the absolute
temperature of 80F. This should be 519.7F; but it is only because of sloppy conversion
from Fahrenheit to Celsius and back. p103 (and p120) "Earth is sailing around the Sun at more than 10,000 mph
(10600 mph on p120) It is actually about 66,675 mph - higher by a factor of 2 Pi (6.28...).
Apparently he used the distance TO the Sun instead of the distance AROUND
the Sun. p106 The idea that "astoundingly realistic pictures of the oceans bottoms" are
created from satellite radar scans of the ocean surface which has
been modified by the gravitational effect of peaks and trenches on
the oceans bottom is absurd. These detailed maps are created from side-scanning SONAR surveys. p124 "... at the bottom of a ten mile shaft you'd weigh about 0.7% less than
at the surface." 10 miles down you are .25% closer to the center of the earth; the
mass of the sphere beneath you has decreased by about .75%.
Since gravity is proportional to Mass divided by the square of
distance, it has decreased about .25% (.9975^3/.9975^2 = .9975).
Apparently Prof. Wolke forgot about the nearness of you. p150 Prof. Wolke lists the speed of sound as 740 mph at 0 deg C, 900 mph
at 20 deg C, and 947 mph at 27 deg. His value at 0 deg is correct, but since speed of sound varies with
the square root of absolute temperature, the other values should be
767 mph and 776 mph.
He is as much as 22% high. p170 "It isn't very unusual for two full moons to fall in the same month;
it happens about four times a year" In fact, it is impossible to have more than 2 BLUE moons in a year;
and then they must be in January and March. Because of the 29.5 day lunar cycle, a blue moon must fall in the
last half day of a 30 day month or the last day and a half of a 31
day month (February is impossible).
4 x .5 + 7 x 1.5 = 12.5 days per year. The chance of
any moon being 'blue' is 12.5 / 365.25 = .0342
There are 365.25 / 29.5 = 12.4 full moons per year.
This comes to .423 blue moons per year or 1 every 2.36 years;
about the same frequency as 4 full moons in one season. p187 "dissolve a half teaspoon of salt in a half cup (250 milliliters) of
water. 1 liter is more than a quart; so a half liter is more than a pint;
so a quarter liter (250 milliliters) is more than a cup. In summary, this book was a lot of fun to read, and has some good science
in it; but his numbers should be taken with a grain (0.065 gm) of salt..
Rating:
Summary: A Little Fast a Little Slow
Review: What Einstein Told His Barber by Robert L. Wolke This book is imaginative and entertaining. It explains in simple terms the hows and whys
of many things we observe often but really don't understand. His editor has done a fine job with spelling and punctuation, but he needs
someone to check his math: p13"In one experiment, out of 500 .30-caliber machine-gun bullets fired
straight upward, only four landed within 10 square feet
(3 square meters) of the gun". While 10 feet is about 3 meters, 10 square feet is about 1 square meter and would
lie within 22 inches of the gun - not a very safe place to wait.
p26-27 "There is a certain speed called the ESCAPE VELOCITY, 25000 mph,
that an object must achieve to circle the Earth in stable orbit and
not fall down."
Actually the speed needed for circular orbit is less by a factor of
the square root of two, about 18000 mph. On p.121 the author has
astronauts orbiting at the proper speed.
Escape velocity launches an object into a parabolic trajectory which
Escapes (imagine that) the earths gravity and never returns. p33 (and p.64) Speed of light 186,000 miles per second (3 million kilometers per second) Oops! That should be 300,000 kilometers per second. p81Author computes 621 degrees Fahrenheit to be twice the absolute
temperature of 80F. This should be 519.7F; but it is only because of sloppy conversion
from Fahrenheit to Celsius and back. p103 (and p120) "Earth is sailing around the Sun at more than 10,000 mph
(10600 mph on p120) It is actually about 66,675 mph - higher by a factor of 2 Pi (6.28...).
Apparently he used the distance TO the Sun instead of the distance AROUND
the Sun. p106The idea that "astoundingly realistic pictures of the oceans bottoms" are
created from satellite radar scans of the ocean surface which has
been modified by the gravitational effect of peaks and trenches on
the oceans bottom is absurd. These detailed maps are created from side-scanning SONAR surveys. p124 "... at the bottom of a ten mile shaft you'd weigh about 0.7% less than
at the surface." 10 miles down you are .25% closer to the center of the earth; the
mass of the sphere beneath you has decreased by about .75%.
Since gravity is proportional to Mass divided by the square of
distance, it has decreased about .25% (.9975^3/.9975^2 = .9975).
Apparently Prof. Wolke forgot about the nearness of you. p150Prof. Wolke lists the speed of sound as 740 mph at 0 deg C, 900 mph
at 20 deg C, and 947 mph at 27 deg. His value at 0 deg is correct, but since speed of sound varies with
the square root of absolute temperature, the other values should be
767 mph and 776 mph.
He is as much as 22% high. p170"It isn't very unusual for two full moons to fall in the same month;
it happens about four times a year" In fact, it is impossible to have more than 2 BLUE moons in a year;
and then they must be in January and March. Because of the 29.5 day lunar cycle, a blue moon must fall in the
last half day of a 30 day month or the last day and a half of a 31
day month (February is impossible).
4 x .5 + 7 x 1.5 = 12.5 days per year. The chance of
any moon being 'blue' is 12.5 / 365.25 = .0342
There are 365.25 / 29.5 = 12.4 full moons per year.
This comes to .423 blue moons per year or 1 every 2.36 years;
about the same frequency as 4 full moons in one season. p187 "dissolve a half teaspoon of salt in a half cup (250 milliliters) of
water. 1 liter is more than a quart; so a half liter is more than a pint;
so a quarter liter (250 milliliters) is more than a cup. In summary, this book was a lot of fun to read, and has some good science
in it; but his numbers should be taken with a grain (0.065 gm) of salt..
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