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PROBLEM 11.116* (Continued)
max
tan 40.2484
xu
PROBLEM 11.117
The velocities of skiers A and B are
as shown. Determine the velocity
of A with respect to B.
SOLUTION
PROBLEM 11.118
The three blocks shown move with constant velocities. Find the velocity of each
block, knowing that the relative velocity of A with respect to C is 300 mm/s upward
and that the relative velocity of B with respect to A is 200 mm/s downward.
SOLUTION
C
PROBLEM 11.119
Three seconds after automobile B passes through the intersection shown,
automobile A passes through the same intersection. Knowing that the speed
of each automobile is constant, determine (a) the relative velocity of B with
respect to A, (b) the change in position of B with respect to A during a 4-s
interval, (c) the distance between the two automobiles 2 s after A has
passed through the intersection.
SOLUTION
A
PROBLEM 11.119 (Continued)
PROBLEM 11.120
Shore-based radar indicates that a ferry leaves its slip with a
velocity
18 km/h
v
70°, while instruments aboard the
ferry indicate a speed of 18.4 km/h and a heading of 30° west
of south relative to the river. Determine the velocity of the
river.
SOLUTION
PROBLEM 11.121
Airplanes A and B are flying at the same altitude and are
tracking the eye of hurricane C. The relative velocity of C
with respect to A is
/
350 km/h
CA v
75°, and the relative
velocity of C with respect to B is
/
400 km/h
CB v
40°.
Determine (a) the relative velocity of B with respect to A,
(b) the velocity of A if ground-based radar indicates that the
hurricane is moving at a speed of 30 km/h due north, (c) the
change in position of C with respect to B during a 15-min
interval.
SOLUTION
BA
PROBLEM 11.121 (Continued)
CB
PROBLEM 11.122
Instruments in an airplane which is in level flight indicate that the velocity relative
to the air (airspeed) is 120 km/h and the direction of the relative velocity vector
(heading) is 70° east of north. Instruments on the ground indicate that the velocity of
the airplane (ground speed) is 110 km/h and the direction of flight (course) is 60°
east of north. Determine the wind speed and direction.
SOLUTION
A
Problem 11.123
Knowing that at the instant shown
block B has a velocity of 2 ft/s to
the right and an acceleration of 3
ft/s
2
to the left, determine (a) the
velocity of block A, (b) the
acceleration of block A.
A
A
PROBLEM 11.124
Knowing that at the instant shown block A has a velocity of 8
in./s and an acceleration of 6 in./s
2
both directed down the
incline, determine (a) the velocity of block B, (b) the
acceleration of block B.
B
* Note the orientation of the coordinate axes on the sketch of the system.
PROBLEM 11.125
A boat is moving to the right with a constant
deceleration of 0.3 m/s
2
when a boy standing on the
deck D throws a ball with an initial velocity relative to
the deck which is vertical. The ball rises to a maximum
height of 8 m above the release point and the boy must
step forward a distance d to catch it at the same height
as the release point. Determine (a) the distance d,
(b) the relative velocity of the ball with respect to the
deck when the ball is caught.
SOLUTION
/
BD y
/
BD
PROBLEM 11.126
The assembly of rod A and wedge B starts from rest and moves
to the right with a constant acceleration of 2 mm/s
2
. Determine
(a) the acceleration of wedge C, (b) the velocity of wedge C
when
10 s.t
SOLUTION
C
PROBLEM 11.127
Determine the required velocity of the belt B if the
relative velocity with which the sand hits belt B is to be
(a) vertical, (b) as small as possible.
SOLUTION
B
PROBLEM 11.128
Conveyor belt A, which forms a 20° angle
with the horizontal, moves at a constant
speed of 4 ft/s and is used to load an
airplane. Knowing that a worker tosses
duffel bag B with an initial velocity of 2.5
ft/s at an angle of 30° with the horizontal,
determine the velocity of the bag relative to
the belt as it lands on the belt.
SOLUTION
PROBLEM 11.128 (Continued)
PROBLEM 11.129
During a rainstorm the paths of the raindrops appear to form an angle of 30° with the vertical and to be directed
to the left when observed from a side window of a train moving at a speed of 15 km/h. A short time later, after
the speed of the train has increased to 24 km/h, the angle between the vertical and the paths of the drops
appears to be 45°. If the train were stopped, at what angle and with what velocity would the drops be observed
to fall?
Rx
PROBLEM 11.129 (Continued)
3.706
tan 21.294
RT
RT
Substitute /2RT
v back into equation for .
R
v
2.71
5.96 m/s
PROBLEM 11.130
Instruments in airplane A indicate that with respect to the air the plane is headed
o
30
north of east with an airspeed of 300 mi/h. At the same time radar on ship B indicates
that the relative velocity of the plane with respect to the ship is 280 mi/h in the
direction
o
33 north of east. Knowing that the ship is steaming due south at 12 mi/h,
determine (a) the velocity of the airplane, (b) the wind speed and direction.
SOLUTION
W
PROBLEM 11.131
When a small boat travels north at 5 km/h, a flag mounted on
its stern forms an angle
50
with the centerline of the boat
as shown. A short time later, when the boat travels east at 20
km/h, angle
is again 50°. Determine the speed and the
direction of the wind.
SOLUTION
