Answers to homework problems:

Chapter 1.
 4) a) different ounces used for volumeand weight measurements
    b) avoirdupois lb = 16 oz, troy lb = 12 oz
35)   8 ft 11 in = 8*12+11 in = 107 in * 2.54 cm/in =271.78 cm = 2.72 m
      439 lb = 439 lb * (1/2.2) kg/lb = 199.55 kg
      47 cm = 47 cm * (1/2.54) in/cm = 18.5 in
38)  a) 16 km/h for each 10 miles/h
     b) 55 mi/h = 55 mi/h * 1.609 km/h = 88.5 km/h
     c) 65 mi/h = 65 mi/h * 1.609 km/h = 104.6 km/h
52)  a) 300 x 50 x 30 cubits = 150 x 25 x 15 yards = 137 x 22.9 x 13.7 m
     b) 137*22.9*13.7 m^3 = 4.3 *10^4 m^3

Chapter 2.
10)   t = d/v = 300 km / 125 km/h = 2.4 h
17)   t = d/v = 3.50 km / 340 m/s = 3.5 km / 0.340 km/s = 10.3 s
22)   t = d/v = 5000 mi / 4 cm/y = 5000 mi * 1.609 km/mi / 0.00004 km/y =
              = 2 *10^8 y
70)   assuming free fall i.e., initial velocity = 0 
      y= 1/2 gt^2   ---> t =sqrt(2y/g)
   a) t1(World Trade Center)    = sqrt (2*417 m /9.8 m/s^2) = 9.23 s
      t2(Empire State Building) = sqrt (2*381 m /9.8 m/s^2) = 8.82 s
      delta =t1-t2 = 9.23 s - 8.82 s = 0.41 s
   b) t3(Sear's Tower) = sqrt (2*443 m /9.8 m/s^2) = 9.51 s