Phys 102 College Physics II Name:

Phys 102 College Physics II Name:  ______________________________________________
Additional Exercises on Chapter 11: Rotational Dynamics and Static Equilibrium
1) A man is holding an 8.00-kg vacuum cleaner at arm's length, a distance of 0.550 m from his shoulder. What is
the torque on the shoulder joint if the arm is horizontal?
A) 4.40 Nm B) 43.2 Nm C) 14.5 Nm D) 0 Nm E) 0.242 Nm
2) A 15.0-kg child is sitting on a playground teeter-totter, 1.50 m from the pivot. What force, applied 0.300 m on
the other side of the pivot, is needed to make the child lift off the ground?
A) 75.0 N B) 66.2 N C) 44.1 N D) 736 N E) 22.5 N
3) The drive chain in a bicycle is applying a torque of 0.850 Nm to the wheel of the bicycle. Treat the wheel as a
hoop with a mass of 0.750 kg and a radius of 33.0 cm. What is the angular acceleration of the wheel?
A) 1.06 rad/s2 B) 20.8 rad/s2 C) 3.43 rad/s2 D) 10.4 rad/s2 E) 5.20 rad/s2
4) In a lab experiment, a student brings up the rotational speed of a rotational motion apparatus to 30.0 rpm. She
then allows the apparatus to slow down on its own, and counts 240 revolutions before the apparatus comes to a
stop. The moment of inertia of the flywheel is 0.0850 kg·m2. What is the retarding torque on the flywheel?
A) 0.000278 Nm
B) 0.0425 Nm
C) 0.0000136 Nm
D) 0.159 Nm
E) 0.0787Nm
Figure 11-5
5) An 82.0 kg-diver stands at the edge of a light 5.00-m diving board, which is supported by two pillars 1.60 m
apart, as shown in Figure 11-5. Find the force exerted by pillar A.
A) 2.51 kN downwards
B) 1.71 kN downwards
C) 3.44 kN upwards
D) 1.71 kN upwards
E) 2.51 kN upwards
1Figure 11-6
6) A store's sign, with a mass of 20.0 kg and 3.00 m long, has its center of gravity at the center of the sign. It is
supported by a loose bolt attached to the wall at one end and by a wire at the other end, as shown in Figure
11-6. The wire makes an angle of 25.0° with the horizontal. What is the tension in the wire?
A) 196 N B) 464 N C) 297 N D) 232 N E) 116 N
Figure 11-7
7) A child is trying to stack two uniform wooden blocks, 12 cm in length, so they will protrude as much as possible
over the edge of a table, without tipping over, as shown in Figure 11-7. What is the maximum possible
overhang distance?
A) 8 cm B) 6 cm C) 9 cm D) 5 cm E) 7 cm
8) A 350-g air track cart on a horizontal air track is attached to a string that goes over a pulley with a moment of
inertia of 6.00 × 10-6 kg·m2 and a radius of 1.35 cm. The string is pulled vertically downward by a force of 2.50
N. What is the acceleration of the cart?
A) 5.27 m/s2 B) 3.27 m/s2 C) 6.53 m/s2 D) 7.14 m/s2 E) 4.98 m/s2
9) A 350-g air track cart on a horizontal air track is attached to a string that goes over a pulley with a moment of
inertia of 6.00 x 10-6 kg·m2 and a radius of 1.35 cm. The string is pulled vertically downward by a force of 2.50
N. What is the tension in the string between the pulley and the cart?
A) 2.50 N B) 2.29 N C) 1.74 N D) 4.58 N E) 1.85 N
210) A mass of 375 g hangs from a string that is wrapped around the circumference of a pulley with a moment of
inertia of 0.0125 kg·m2 and a radius of 26.0 cm. When the mass is released, the mass accelerates downward
and the pulley rotates about its axis as the string unwinds. What is the tension in the string?
A) 1.21 N B) 2.45 N C) 1.84 N D) 0.605 N E) 3.68 N
11) A 330-g air track cart on a horizontal air track is attached to a string that goes over a pulley with a moment of
inertia of 5.00 × 10-6 kg·m2 and a radius of 1.35 cm. A 255 -g mass hangs from the other end of the string and
is released. What is the acceleration of the cart?
A) 6.53 m/s2 B) 4.08 m/s2 C) 7.14 m/s2 D) 4.74 m/s2 E) 9.72 m/s2
12) A mass of 355 g hangs from one end of a string that goes over a pulley with a moment of inertia of
0.0125 kg·m2 and a radius of 15.0 cm. A mass of 680 g hangs from the other end. When the masses are
released, the larger mass accelerates downward, the lighter mass accelerates upward, and the pulley turns
without the string slipping on the pulley. What is the acceleration of the masses?
A) 3.82 m/s2 B) 2.00 m/s2 C) 2.87 m/s2 D) 5.74 m/s2 E) 7.78 m/s2
13) The torque required to turn the crank on an ice cream maker is 4.50 Nm. How much work does it take to turn
the crank through 300 full turns?
A) 8480 J B) 4240 J C) 2700 J D) 1350 J E) 2120 J
Figure 11-9
14) The L-shaped object shown in Figure 11-9 consists of the masses connected by light rods. How much work
must be done to accelerate the object from rest to an angular speed of 3.25 rad/s about the  y-axis?
A) 374 J B) 42.2 J C) 173 J D) 27.4 J E) 86.5 J
15) A torque of 0.12 N·m is applied to an egg beater.  (a) If the egg beater starts at rest, what is its angular
momentum after 0.50 s? (b) If the moment of inertia of the egg beater is 2.5 x 10-3 kg·m2 what is its angular
speed after 0.50 s?
16) A circular saw blade accelerates from rest to an angular speed of 3620 rpm in 6.30 revolutions. (a) Find the
torque exerted on the saw blade, assuming it is a disk of radius 15.2 cm and mass 0.755 kg. (b) Is the angular
speed of the saw blade after 3.15 revolutions greater than, less than, or equal to 1810 rpm?  Explain. (c) Find the
angular speed of the blade after 3.15 revolutions.
3Answer Key
Testname: ADDITIONAL EXERCISES ON CHAPTER 11
1) B
2) D
3) D
4) A
5) B
6) D
7) C
8) C
9) B
10) A
11) B
12) B
13) A
14) C
15) (a) 0.060 kg·m2/s; (b) 24 rad/s
16) (a) 15.8 N·m; (b) greater than; (c) 2560 rev/min
4