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PROBLEM 11.131 (Continued)
PROBLEM 11.132
As part of a department store
display, a model train D runs on a
slight incline between the store’s
up and down escalators. When the
train and shoppers pass Point A,
the train appears to a shopper on
the up escalator B to move
downward at an angle of 22° with
the horizontal, and to a shopper
on the down escalator C to move
upward at an angle of 23° with the
horizontal and to travel to the left.
Knowing that the speed of the
escalators is 3 ft/s, determine the
speed and the direction of the
train.
PROBLEM 11.132 (Continued)
PROBLEM 11.133
Determine the smallest radius that should be used for a
highway if the normal component of the acceleration of a car
traveling at 72 km/h is not to exceed 2
0.8 m/s .
PROBLEM 11.134
Determine the maximum speed that the cars of the roller-coaster
can reach along the circular portion AB of the track if
is 25 m
and the normal component of their acceleration cannot exceed 3 g.
Problem 11.135
Human centrifuges are often used to simulate different
acceleration levels for pilots and astronauts. Space shuttle
pilots typically face inwards towards the center of the gondola
in order to experience a simulated 3g forward acceleration.
Knowing that the astronaut sits 5 m from the axis of rotation
and experiences 3 g’s inward, determine her velocity.
A
PROBLEM 11.136
The diameter of the eye of a stationary hurricane is 20 mi and the
maximum wind speed is 100 mi/h at the eye wall, r 10 mi.
Assuming that the wind speed is constant for constant r and
decreases uniformly with increasing r to 40 mi/h at r 110 mi,
determine the magnitude of the acceleration of the air at (a) r 10
mi, (b) r 60 mi, (c) r 110 mi.
PROBLEM 11.137
The peripheral speed of the tooth of a 10-in.-diameter circular saw blade is 150 ft/s when the power to the saw
is turned off. The speed of the tooth decreases at a constant rate, and the blade comes to rest in 9 s. Determine
the time at which the total acceleration of the tooth is 2
130 ft/s .
PROBLEM 11.138
A robot arm moves so that P travels in a circle about Point B,
which is not moving. Knowing that P starts from rest, and its speed
increases at a constant rate of 10 mm/s2, determine (a) the
magnitude of the acceleration when t 4 s, (b) the time for the
magnitude of the acceleration to be 80 mm/s2.
PROBLEM 11.139
A monorail train starts from rest on a curve of radius 400 m and accelerates at the constant rate .
t
a If the
maximum total acceleration of the train must not exceed 2
1.5 m/s , determine (a) the shortest distance in
which the train can reach a speed of 72 km/h, (b) the corresponding constant rate of acceleration .
t
a
