Solusi soal PRD hal 32 by kelompok 5

Solution PRD exercise page 32

1. Need : 5 gallons can =           mouthful

Know: Conversion 1.00 ft= 12.00 inches & 1 gallon= 0.134 ft³

How: Use units analysis

Solve :

2.     Need: For each part, conversion is ___________ (state whether definition, conversion factor, geometry, or scientific law)

Know: Basic concept s of conversion factors, geometry and scientific laws. Also the diameter of the Earth ¹is 12.756 km

How: For conversions use units method

Solve :

3. Need: Height 13 hands = ________ ft.

Know: Conversion factors: 16 hands/fathom and 6.0 ft/fathom.

How: Method of units

Solve :

4. Need: Square mile = ________ acres.

Know: Conversion factors: 1609 m/mile, 10⁴m²/hectare.

A team could plough 0.4 hectares/day = 1 acre/day. Thus 1.0 hectare =

2.5 acres.

How : Method of units

Solve :

5. Need : Area of orange skin =                 m²

Know: 39 inches/m

How : Method of units and a spherical orange whose surface area is πD²

6.Need:Volume of apple = ________ in3.

Know:Conversion factors:  39 inches/m and 100 cm/m.

How:Method of units and assume a spherical apple whose volume is

πD3/6.

7.  Need:Tire pressure in SI units (N/m2)

Know:Use convert.exe2

for unit conversions. 1.00 lbf/in2= 6895 N/m2.

How:Method of units

8. Need: Wt of 50.0 slugs in lbf

Know: 1.00 slug is defined as F/g with F in lbf and g in 

How: Use eqn 2.3 of text

9.      9. Need: Mass of 5.0 slug on the Moon

Know - How: Mass is a property

Solve: m = 5.00 slugs anywhere in the Universe.

     10 .Need: Force on a body of mass 856 g (= 0.856 kg) accelerated at 9.81 m/s²

Know: Newton’s Law of Motion, F = ma

How: F in N, m in kg and a in m/s² 

11. Need: Wt of body on the Moon

Know: Mass = 0.102 kg, acceleration = 1.64 m/s²

How:Newton’s Law of Motion, F = ma or W= mg_moon

12. Need:Force to accelerate 735 lbm by 15.0 m/s²

Know: Need proportionality constant, gc= 32.2 lbm ft/lbf s²

How: Newton’s Law of Motion, F = ma/gc

13. Need:Value and units of g_c in the Engineering English system on the Moon

Know – How: g_c is a proportionality constant to convert units.

14. Need:Acceleration of car = ________ g’s.

Know:1.0g= 9.8 m/s²and acceleration is the rate of change of speed withtime.

How:Method of units and conversion factor of 60. mph = 88 ft/s (i.e.,

60/3600 ×5280 [miles/hr][hours/s][ft/mile].Also that 1 ft = 0.3048 m.

15. Need:Ratio of body mass in kg/weight in pounds = ________ kg/lbf. 

Know: assume your mass in Mkg. Conversion factor = 2.20 lbm/kg. Also weight is a force that, in the English Engineering system, is mg/gc where m is your body mass in lbm. 

How:Method of units and weight is a force that, in the English 

Engineering system, is W= mg/gc where m is your body mass in lbm.

16. Need:Power of car = ________ W. 

Know:Power of 1W = 1 J/s and 1 J = 1 N ×1 m, speed in m/s. 

How:Method of units and 1 watt of power = 1 (N ×m)/s = 1 (N ×m/s)

17. Need: Time to 60.0 mph (26.8 m/s) and # of g’s on a rocket sled.

Know:Newton’s law, a = F/m; g= 9.81 m/s²

. Also t = v/a(v is speed) since a= v/t.

How:Method of units and inverted Newton’s law expressed in # g’s = a/g =

(F/m)g= F/mg.

 18.Need: Mass of crate = _________ lbm.

19.Need: a) Massa of moon apple=_________lbm and

b) weight of moon apple=________lbf

Nama Anggota Kelompok 5 (Kelas 10 PRD)

1. Arsi Amallah Binhaq (16514059)

2. Ahmad Sena Musa Satria(16514359)

3. Nur Latifah Ulfah(16514347)

4.Lara Yudillah(16514221)

5.Siti Sundari Fatimah(16514107)

Reference: Exploring Engineering second edition by Philip Kosky