9. We first solve the equation for k
.
The factor 4 p2 is dimensionless so dimensional analysis gives
.
13. The total weight is given by the sum
Wttot = Wtbass + Wtcod + Wtsal.
Taking the direct sum gives
Wttot = 2.65 lb + 10.1 lb + 17.23 lb = 29.98 lb.
This result must be rounded to the proper number of significant figures. The 10.1 lb cod gives us only one decimal place. Therefore, the result must be rounded to one decimal place:
Wttot = 30.0 lb
15. The area of a circle is given by the expression A = pr2. The value of p is known to many significant digits. The number of significant digits in the results is limited only by the number in the radius r. In each case, we need only to use more significant digits in p than in r to obtain the most accurate result available.
(a) A = (3.1416)(5.342 m)2 = 89.65 m2
(b) A = (3.14)(2.7 m)2 = 23 m2
29. (a) For this part we only need to convert meters to feet
(b) For this part both the distance and time units must be converted
33. (a) From the given information, the surface of the earth must move through the 3000 miles in the 3-hour time difference. Thus we have for the rotational speed,
(b) The earth completes one rotation in 24 hours. Given the above rotational speed, we can say
(c) The circumference of a circle is given by Circum. = 2pr
Selected Solutions by David Reid, Eastern Michigan University. ©2002 by Prentice Hall, Inc.
