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of McGraw-Hill, and must be surrendered upon request of McGraw-Hill. Any duplication or distribution, either in print or electronic form, without the
permission of McGraw-Hill, is prohibited.
Dynamics 2e 567
Problem 3.101
The driver of the truck suddenly applies the brakes, and the truck comes to a stop. During braking, either
the crate slides or it does not. Considering the forces acting on the truck during braking, will the truck stop
in a shorter distance (or time) if the crate slides, or will the distance (or time) be shorter if it does not?
Justify your answer.
of McGraw-Hill, and must be surrendered upon request of McGraw-Hill. Any duplication or distribution, either in print or electronic form, without the
permission of McGraw-Hill, is prohibited.
568 Solutions Manual
Problem 3.102
A car is being pulled to the right in the two ways shown. Neglecting the inertia of the pulleys and rope, as
well as any friction in the pulleys, if the car is allowed to roll freely, will the acceleration of the car in (a)
be smaller, equal to, or larger than the acceleration of the car in (b)?
of McGraw-Hill, and must be surrendered upon request of McGraw-Hill. Any duplication or distribution, either in print or electronic form, without the
permission of McGraw-Hill, is prohibited.
Dynamics 2e 569
Problem 3.103
Particles
A
and
B
, which are connected with a massless linear spring, have been thrown up in the air and
are moving under the action of the spring force and their own weight. Assuming that no other forces are
affecting the motion of the particles, what will be the acceleration of their center of mass?
Solution
of McGraw-Hill, and must be surrendered upon request of McGraw-Hill. Any duplication or distribution, either in print or electronic form, without the
permission of McGraw-Hill, is prohibited.
570 Solutions Manual
Problem 3.104
Two particles
A
and
B
with masses
mA
and
mB
, respectively, are placed at a distance
r0
from one another.
Assuming that the only force acting on the masses is their mutual gravitational attraction, determine the
acceleration of particle Bas seen from particle A.
Solution
of McGraw-Hill, and must be surrendered upon request of McGraw-Hill. Any duplication or distribution, either in print or electronic form, without the
permission of McGraw-Hill, is prohibited.
Dynamics 2e 571
Problem 3.105
A person lifts the
80 kg
load
A
by pulling down on the rope with a constant force
F
as shown. Neglecting
any source of friction as well as the inertia of the ropes and the pulleys, determine
F
if
A
accelerates
upward at 0:5 m=s2.
Solution
572 Solutions Manual
Problem 3.106
The load
A
weighs
185 lb
. Neglecting any source of friction as well as the inertia of the ropes and
the pulleys, determine the acceleration of
A
if a person pulls down on the rope with a constant force
FD185 lb as shown.
Solution
Dynamics 2e 573
Problem 3.107
A person lifts the
80 kg
load
A
by pulling down on the rope with a constant force
F
as shown. Neglecting
friction, the inertia of the ropes, and the rotational inertia of the pulleys, but accounting for the fact that
pulley Dhas a mass mDD8kg, determine Fif Aaccelerates upward at 2:5 m=s2.
Solution
Referring to the FBDs at the right, we model
A
and pulley
D
as particles subject
only to their respective weights
mAg
and
mDg
as well as the tension in the cord
574 Solutions Manual
Problem 3.108
Revisit Example 3.13 and determine the expression for the accel-
eration of
A
if the load at
P
is replaced by a force with magnitude
equal to the load’s weight, i.e., FDmPg.
Solution
Dynamics 2e 575
Problem 3.109
The motor
M
is at rest when someone flips a switch and it starts pulling in the
rope. The acceleration of the rope is uniform, and it takes
1
s to achieve a re-
traction rate of
4ft=s
. After
1
s the retraction rate becomes constant. Determine
the tension in the cable during and after the initial
1
s interval. The cargo
C
weighs
130 lb
, pulleys
A
and
B
each weigh
12 lb
, and the weight of the ropes
is negligible. Neglect friction in the pulleys and the rotational inertia of the
pulleys.
Solution
As shown on the right, we model the pulleys
A
and
B
and the cargo
C
as particles of masses
mA
,
mB
, and
mC
, respectively. The only
