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PROBLEM 17.48
Knowing that the maximum allowable couple that can be applied to a shaft is 15.5 kip in., determine the
maximum horsepower that can be transmitted by the shaft at (a) 180 rpm, (b) 480 rpm.
PROBLEM 17.49
Three shafts and four gears are used to form a gear train which
will transmit 7.5 kW from the motor at A to a machine tool at F.
(Bearings for the shafts are omitted from the sketch.) Knowing
that the frequency of the motor is 30 Hz, determine the
magnitude of the couple which is applied to shaft (a) AB,
(b) CD, (c) EF.
PROBLEM 17.50
The shaft-disk-belt arrangement shown is used to transmit 2.4 kW from Point
A to Point D. Knowing that the maximum allowable couples that can be
applied to shafts AB and CD are 25 N m
and 80 N m, respectively,
determine the required minimum speed of shaft AB.
PROBLEM 17.51
The drive belt on a vintage sander transmits ½ hp to
a pulley that has a diameter of d = 4 in. Knowing
that the pulley rotates at 1450 rpm, determine the
tension difference T1 – T2 between the tight and
slack sides of the belt.
PROBLEM 17.52
The rotor of an electric motor has a mass of 25 kg, and it is observed that 4.2 min is required for the rotor to
coast to rest from an angular velocity of 3600 rpm. Knowing that kinetic friction produces a couple of
magnitude 1.2 Nm, determine the centroidal radius of gyration for the rotor.
PROBLEM 17.53
A small grinding wheel is attached to the shaft of an electric motor
which has a rated speed of 3600 rpm. When the power is turned off, the
unit coasts to rest in 70 s. The grinding wheel and rotor have a combined
weight of 6 lb and a combined radius of gyration of 2 in. Determine the
average magnitude of the couple due to kinetic friction in the bearings
of the motor.
PROBLEM 17.54
A bolt located 50 mm from the center of an automobile wheel is tightened
by applying the couple shown for 0.10 s. Assuming that the wheel is free to
rotate and is initially at rest, determine the resulting angular velocity of the
wheel. The wheel has a mass of 19 kg and has a radius of gyration of
250 mm.
PROBLEM 17.55
A uniform 144-lb cube is attached to a uniform 136-lb circular shaft as shown and
a couple M of constant magnitude is applied to the shaft when the system is at
rest. Knowing that r 4 in., L 12 in., and the angular velocity of the system is
960 rpm after 4 s, determine the magnitude of the couple M.
PROBLEM 17.56
A uniform 75-kg cube is attached to a uniform 70-kg circular shaft as shown and a
couple M of constant magnitude 20 N m
is applied to the shaft. Knowing that
r 100 mm and L 300 mm., determine the time required for the angular
velocity of the system to increase from 1000 rpm to 2000 rpm.
PROBLEM 17.57
A disk of constant thickness, initially at rest, is placed in contact with a belt
that moves with a constant velocity
v
. Denoting by
k
the coefficient of
kinetic friction between the disk and the belt, derive an expression for the
time required for the disk to reach a constant angular velocity.
