Estudante universitário

CHAPTER TWO
2.1 (a)
= 18144 × 10 9 ms . 1 wk 1 d 1 h 1 s 38.1 ft / s 0.0006214 mi 3600 s (b) = 25.98 mi / h ⇒ 26.0 mi / h 3.2808 ft 1 h 3 wk 7d 24 h 3600 s 1000 ms

(c)

554 m 4 1d 1h d ⋅ kg 24 h 60 min

1 kg 108 cm 4 = 3.85 × 10 4 cm 4 / min⋅ g 1000 g 1 m 4

2.2 (a) (b) (c)

1 m 1 h 760 mi = 340 m / s h 0.0006214 mi 3600 s 921 kg 2.20462 lb m m3 1 kg 1 m3 = 57.5 lb m / ft 3 35.3145 ft 3 1.34 × 10 -3 hp = 119.93 hp ⇒ 120 hp 1 J/s

5.37 × 10 3 kJ 1 min 1000 J min 60 s 1 kJ

2.3 Assume that a golf ball occupies the space equivalent to a 2 in × 2 in × 2 in cube. For a classroom with dimensions 40 ft × 40 ft × 15 ft : 40 × 40 × 15 ft 3 (12) 3 in 3 1 ball n balls = . = 518 × 10 6 ≈ 5 million balls ft 3 2 3 in 3 The estimate could vary by an order of magnitude or more, depending on the assumptions made. 2.4 4.3 light yr 365 d 24 h
1 yr 1d 3600 s 1.86 × 10 5 mi 1 h 1 s 3.2808 ft 0.0006214 mi 1 step = 7 × 1016 steps 2 ft

2.5 Distance from the earth to the moon = 238857 miles
238857 mi 1 m 1 report 0.001 m 0.0006214 mi = 4 × 1011 reports

2.6

19 km 1000 m 0.0006214 mi 1000 L = 44.7 mi / gal 1 L 1 km 1 m 264.17 gal Calculate the total cost to travel x miles. Total Cost
American

= $14,500 +

$1.25 1 gal gal 28 mi

x (mi)

= 14,500 + 0.04464 x

Total Cost

European

= $21,700 +

$1.25 1 gal x (mi) = 21,700 + 0.02796 x gal 44.7 mi

Equate the two costs ⇒ x = 4.3 × 10 5 miles

2-1

2.7
5320 imp. gal plane ⋅ h = 1.188 × 105 14 h 365 d 1 d 1 yr 106 cm3 220.83 imp. gal 0.965 g 1 cm
3

1 kg 1000 g

1 tonne 1000 kg

tonne kerosene plane ⋅ yr

4.02 × 109 tonne crude oil 1 tonne kerosene yr
5

plane ⋅ yr

7 tonne crude oil 1.188 × 10 tonne kerosene

= 4834 planes ⇒ 5000 planes

2.8 (a) (b) (c)

25.0 lb m 25 N

32.1714 ft / s 2 1

1

lb f

32.1714 lb m ⋅ ft / s 2 1 kg ⋅ m/s 2 1N 9.8066 m/s 2

= 25.0 lb f

= 2.5493 kg ⇒ 2.5 kg

10 ton

1 lb m 5 × 10
-4

1000 g ton 2.20462 lb m 85.3 lb m 1 ft 3 1 m3