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PROBLEM 13.9
A package is projected up a
15°
incline at A with an initial
velocity of 8 m/s. Knowing that the coefficient of kinetic
friction between the package and the incline is 0.12, determine
(a) the maximum distance d that the package will move up the
incline, (b) the velocity of the package as it returns to its
original position.
PROBLEM 13.10
A 1.4 kg model rocket is launched vertically from rest with a constant thrust of 25 N until the rocket reaches
an altitude of 15 m and the thrust ends. Neglecting air resistance, determine (a) the speed of the rocket when
the thrust ends, (b) the maximum height reached by the rocket, (c) the speed of the rocket when it returns to
the ground.
PROBLEM 13.11
Packages are thrown down an incline at A with a velocity of 1
m/s. The packages slide along the surface ABC to a conveyor
belt which moves with a velocity of 2 m/s. Knowing that
0.25
k
m
=
between the packages and the surface ABC,
determine the distance d if the packages are to arrive at C with
a velocity of 2 m/s.
PROBLEM 13.12
Packages are thrown down an incline at A with a velocity of
1 m/s. The packages slide along the surface ABC to a conveyor
belt which moves with a velocity of 2 m/s. Knowing that
7.5 md=
and
0.25
k
m
=
between the packages and all
surfaces, determine (a) the speed of the package at C, (b) the
distance a package will slide on the conveyor belt before it
comes to rest relative to the belt.
PROBLEM 13.12 (Continued)
(2)(0.25)(9.81)
belt
PROBLEM 13.13
Boxes are transported by a conveyor belt with a velocity v0 to
a fixed incline at A where they slide and eventually fall off at
B. Knowing that
0.40,
k
m
=
determine the velocity of the
conveyor belt if the boxes leave the incline at B with a velocity
of 8 ft/s.
PROBLEM 13.14
Boxes are transported by a conveyor belt with a velocity v0 to
a fixed incline at A where they slide and eventually fall off at
B. Knowing that
0.40,
k
m
=
determine the velocity of the
conveyor belt if the boxes are to have zero velocity at B.
PROBLEM 13.15
A 1200-kg trailer is hitched to a 1400-kg car. The car and trailer are
traveling at 72 km/h when the driver applies the brakes on both the car
and the trailer. Knowing that the braking forces exerted on the car and
the trailer are 5000 N and 4000 N, respectively, determine (a) the
distance traveled by the car and trailer before they come to a stop,
(b) the horizontal component of the force exerted by the trailer hitch
on the car.
PROBLEM 13.16
A trailer truck enters a 2 percent uphill grade traveling at 72 km/h and reaches a speed of 108 km/h in 300 m.
The cab has a mass of 1800 kg and the trailer 5400 kg. Determine (a) the average force at the wheels of the
cab, (b) the average force in the coupling between the cab and the trailer.
PROBLEM 13.17
The subway train shown is traveling at a speed of 30 mi/h when
the brakes are fully applied on the wheels of cars B and C,
causing them to slide on the track, but are not applied on the
wheels of car A. Knowing that the coefficient of kinetic friction
is 0.35 between the wheels and the track, determine (a) the
distance required to bring the train to a stop, (b) the force in
each coupling.
