PROBLEM 12.133* (Continued)
PROBLEM 12.133* (Continued)
PROBLEM 12.CQ1
A 1000 lb boulder B is resting on a 200 lb platform A when truck
C accelerates to the left with a constant acceleration. Which of
the following statements are true (more than one may be true)?
(a) The tension in the cord connected to the truck is 200 lb
(b) The tension in the cord connected to the truck is 1200 lb
(c) The tension in the cord connected to the truck is greater
than 1200 lb
(d) The normal force between A and B is 1000 lb
(e) The normal force between A and B is 1200 lb
(f) None of the above
SOLUTION
PROBLEM 12.CQ2
Marble A is placed in a hollow tube, and the tube is swung in a horizontal
plane causing the marble to be thrown out. As viewed from the top, which
of the following choices best describes the path of the marble after leaving
the tube?
(a) 1
(b) 2
(c) 3
(d) 4
(e) 5
PROBLEM 12.CQ3
The two systems shown start from rest. On
the left, two 40 lb weights are connected
by an inextensible cord, and on the right,
a constant 40 lb force pulls on the cord.
Neglecting all frictional forces, which of
the following statements is true?
(a) Blocks A and C will have the same
acceleration
(b) Block C
will have a larger
acceleration than block A
(c) Block A
will have a larger
acceleration than block C
(d) Block A will not move
(e) None of the above
PROBLEM 12.CQ4
The system shown is released from rest in the position shown. Neglecting
friction, the normal force between block A and the ground is
(a) less than the weight of A plus the weight of B
(b) equal to the weight of A plus the weight of B
(c) greater than the weight of A plus the weight of B
PROBLEM 12.CQ5
People sit on a Ferris wheel at Points A, B, C and D. The Ferris wheel
travels at a constant angular velocity. At the instant shown, which
person experiences the largest force from his or her chair (back and
seat)? Assume you can neglect the size of the chairs, that is, the people
are located the same distance from the axis of rotation.
(a) A
(b) B
(c) C
(d) D
(e) The force is the same for all the passengers.
ma.
PROBLEM 12.CQ6
A uniform crate C with mass mC is being
transported to the left by a forklift with a
constant speed v1. What is the magnitude
of the angular momentum of the crate
about Point D, that is, the upper left
corner of the crate?
(a) 0
(b) mv1a
(c) mv1b
(d)
22
1bamv +
PROBLEM 12.CQ7
A uniform crate C with mass mC is being
transported to the left by a forklift with
a constant speed v1. What is the
magnitude of the angular momentum of
the crate about Point A, that is, the point
of contact between the front tire of the
forklift and the ground?
(a) 0
(b) mv1d
(c) 3mv1
(d)
22
13mv d+
PROBLEM 12.F1
Crate A is gently placed with zero initial velocity onto a moving
conveyor belt. The coefficient of kinetic friction between the crate and
the belt is
µ
k. Draw the FBD and KD for A immediately after it
contacts the belt.
SOLUTION
PROBLEM 12.F2
Two blocks weighing WA and WB are at rest on a conveyor that is initially at
rest. The belt is suddenly started in an upward direction so that slipping
occurs between the belt and the boxes. Assuming the coefficient of friction
between the boxes and the belt is
µ
k, draw the FBDs and KDs for blocks
A and B. How would you determine if A and B remain in contact?