Solution hibeller dinâmica 10 edição

Table of Contents
Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 1 145 242 302 396 504 591 632 666 714 786

Engineering Mechanics - Dynamics

Chapter 12

Problem 12-1 A truck traveling along a straight road at speed v1, increases its speed to v2 in time t. If its acceleration is constant, determine the distance traveled. Given: v1 = 20 Solution: a = v2 − v1 t 1 2 at 2 a = 1.852 m s
2

km hr

v2 = 120

km hr

t = 15 s

d = v1 t +

d = 291.67 m

Problem 12-2 A car starts from rest and reaches a speed v after traveling a distance d along a straight road. Determine its constant acceleration and the time of travel. Given: Solution: v = 2a d
2

v = 80

ft s
2

d = 500 ft

v a = 2d t = v a

a = 6.4

ft s
2

v = at

t = 12.5 s

Problem 12-3 A baseball is thrown downward from a tower of height h with an initial speed v0. Determine the speed at which it hits the ground and the time of travel. Given: h = 50 ft Solution: v = v0 + 2g h
2

g = 32.2

ft s
2

v0 = 18

ft s

v = 59.5

ft s

1

Engineering Mechanics - Dynamics

Chapter 12

t =

v − v0 g

t = 1.29 s

*Problem 12–4 Starting from rest, a particle moving in a straight line has an acceleration of a = (bt + c). What is the particle’s velocity at t1 and what is its position at t2? Given: Solution: a ( t) = b t + c v ( t1 ) = 0 m s ⌠ v ( t ) = ⎮ a ( t ) dt ⌡0 d ( t2 ) = 80.7 m t b = 2

m s
3

c = −6

m s
2

t1 = 6 s

t2 = 11 s

⌠ d ( t ) = ⎮ v ( t ) dt ⌡0

t

Problem 12-5 Traveling with an initial speed v0 a car accelerates at rate a along a straight road. How long will it take to reach a speed vf ? Also, through what distance does the car travel during this time? Given: Solution: vf = v0 + a t
2 2

v0 = 70

km hr

a = 6000

km hr
2

vf = 120

km hr

t =

vf − v0 a
2 2

t = 30 s

vf = v0 + 2a s

vf − v0 s = 2a

s = 792 m