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PROBLEM 13.CQ5
The expected damages associated with two types of perfectly plastic collisions are to be
compared. In the first case, two identical cars traveling at the same speed impact each
other head on. In the second case, the car impacts a massive concrete wall. In which case
would you expect the car to be more damaged?
(a) Case 1
(b) Case 2
(c) The same damage in each case
SOLUTION
PROBLEM 13.CQ6
A 5 kg ball A strikes a 1 kg ball B that is initially at rest. Is it
possible that after the impact A is not moving and B has a speed
of 5v?
(a) Yes
(b) No
Explain your answer.
SOLUTION
PROBLEM 13.F1
The initial velocity of the block in position A is 30 ft/s. The coefficient
of kinetic friction between the block and the plane is
m
k = 0.30. Draw
impulse-momentum diagrams that could be used to determine the time
it takes for the block to reach B with zero velocity, if
θ
= 20°.
SOLUTION
PROBLEM 13.F2
A 4-lb collar which can slide on a frictionless vertical rod is
acted upon by a force P which varies in magnitude as shown.
Knowing that the collar is initially at rest, draw impulse-
momentum diagrams that could be used to determine its
velocity at t = 3 s.
SOLUTION
1
0
t
=
PROBLEM 13.F3
The 15-kg suitcase A has been
propped up against one end of a
40-kg luggage carrier B and is
prevented from sliding down by
other luggage. When the luggage
is unloaded and the last heavy
trunk is removed from the carrier,
the suitcase is free to slide down,
causing the 40-kg carrier to move
to the left with a velocity vB of
magnitude 0.8 m/s. Neglecting
friction, draw impulse-momentum
diagrams that could be used to
determine (a) the velocity of A as
it rolls on the carrier and (b) the
velocity of the carrier after the
suitcase hits the right side of the
carrier without bouncing back.
SOLUTION
Answer:
PROBLEM 13.F4
Car A was traveling west at a speed of 15 m/s and car B was traveling north at an
unknown speed when they slammed into each other at an intersection. Upon
investigation it was found that after the crash the two cars got stuck and skidded
off at an angle of 50° north of east. Knowing the masses of A and B are mA and mB
respectively, draw impulse-momentum diagrams that could be used to determine
the velocity of B before impact.
SOLUTION
Answer:
PROBLEM 13.F5
Two identical spheres A and B, each of mass m, are attached to an inextensible
inelastic cord of length L and are resting at a distance a from each other on a
frictionless horizontal surface. Sphere B is given a velocity v0 in a direction
perpendicular to line AB and moves it without friction until it reaches B' where the
cord becomes taut. Draw impulse-momentum diagrams that could be used to
determine the magnitude of the velocity of each sphere immediately after the cord
has become taut.
yy
AB
PROBLEM 13.F6
A sphere with a speed v0 rebounds after striking a frictionless inclined plane as
shown. Draw impulse-momentum diagrams that could be used to find the velocity
of the sphere after the impact.
SOLUTION
Answer:
PROBLEM 13.F7
An 80-Mg railroad engine A
coasting at 6.5 km/h strikes a 20-
Mg flatcar C carrying a 30-Mg
load B which can slide along the
floor of the car (mk = 0.25). The
flatcar was at rest with its brakes
released. Instead of A and C
coupling as expected, it is observed
that A rebounds with a speed of 2
km/h after the impact. Draw
impulse-momentum diagrams that
could be used to determine (a) the
coefficient of restitution and the
speed of the flatcar immediately
after impact, and (b) the time it
takes the load to slide to a stop
relative to the car.
SOLUTION
Answer:
(a) Look at A and C (the friction force between B and C is not impulsive) to find the velocity after impact.
PROBLEM 13.F8
Two frictionless balls strike each other as shown. The coefficient of restitution
between the balls is e. Draw the impulse-momentum diagrams that could be used
to find the velocities of A and B after the impact.
SOLUTION
Answer:
PROBLEM 13.F9
A 10-kg ball A moving horizontally at 12 m/s strikes a 10-kg block B. The
coefficient of restitution of the impact is 0.4 and the coefficient of kinetic
friction between the block and the inclined surface is 0.5. Draw impulse-
momentum diagrams that could be used to determine the speeds of A and B
after the impact.
SOLUTION
Answer:
PROBLEM 13.F10
Block A of mass mA strikes ball B of mass mB with a speed of vA as shown.
Draw impulse-momentum diagrams that could be used to determine the speeds
of A and B after the impact and the impulse during the impact.
SOLUTION
Answer:
