Wade Fisher - PHY231, Fall 2012 - Introductor 3

Wade Fisher - PHY231, Fall 2012 - Introductor
Exam2_Practice2
3
1 pt
A puck of mass m is attached by a string which passes through
a hole on a frictionless surface. The other end of the string is
held by a student. The puck initially slides on the frictionless
surface in a circular path of radius 5 m as shown in the figure.
The initial angular momentum of the mass is 8 kg-mˆ2/s
and the initial rotational kinetic energy of the mass is 9 J.
Then the student pull on the string and reduces the radius
to 4 m. What is the final angular momentum (in kg-mˆ2/s)?
1. A 3.3
B 4.1
C 5.1
E 8.0
F 10.0
G 12.5
What is the final kinetic energy (in J)?
2. A 3.4
E 10.6
D 6.4
H 15.6
B 4.5
C 6.0
D 7.9
F 14.1
G 18.7
H 24.9
1 pt A 21.9 kg. boy skating in the positive x direction at 4.2
m/s on frozen lake collides with a stationary 193.4 kg man.
After the collision, the boy moves at a velocity 1.974 m/s in
the negative x direction. The man ends up with a velocity of
_______ in the positive x direction. (This collision is not
elastic.) (in m/s)
3. A 0.699
E 1.707
B 0.874
C 1.092
D 1.365
F 2.134
G 2.667
H 3.334
1 pt The motor for a toy Ferris wheel creates a torque of 15
Nm. The wheel requires 27 seconds to reach its design frequency of one revolution per 10 seconds. What is the moment
of inertia of the wheel? (in kg · m2 )
4. A 645 B 754 C 882 D 1032
E 1208 F 1413 G 1653 H 1935
Wade Fisher - PHY231, Fall 2012 - Introductor
Exam2_Practice2
5
1 pt A pendulum has a period of 2.17 s on the planet Ovid
where the acceleration of gravity is 11.5 m/s2. What is its
period on the surface of Ovid’s moon Elsie where g = 3.45
m/s2? (in s)
5. A 2.98
E 9.32
B 3.96
C 5.27
D 7.01
F 12.40
G 16.49
H 21.93
1 pt Sarah weighs 483.1 N on Earth. What would be her
weight on planet X, if planet X has 5 times the mass of Earth
and 4 times the radius of Earth? (in N)
6. A 129.0
E 241.8
B 151.0
C 176.6
D 206.7
F 282.9
G 331.0
H 387.3
1 pt A supersonic airplane is flying horizontally at a speed
of 2520 km/h. What is the centripetal acceleration of the
airplane, if it turns from North to East on a circular path
with a radius of 87.5 km?
(in m/s^2)
7. A 4.09
D 6.55
G 1.05 × 101
B 4.79
C 5.60
E 7.67
F 8.97
H 1.23 × 101
1 pt How much time does the turn take?
(in min)
8. A 1.85
D 4.35
G 1.02 × 101
B 2.46
C 3.27
E 5.79
F 7.70
H 1.36 × 101
1 pt How much distance does the airplane cover during the
turn?
(in km)
9. A 4.58 × 101
D 7.33 × 101
G 1.17 × 102
B 5.36 × 101
C 6.27 × 101
E 8.58 × 101
F 1.00 × 102
H 1.37 × 102
Wade Fisher - PHY231, Fall 2012 - Introductor
Exam2_Practice2
7
1 pt
⊲ Consider a turntable that has a constant angular acceleration of 1 rad/sˆ2 and a instantaneous angular velocity of 1
rad/s. A mass attached to this turntable at a distance of 1
m from the axis of rotation will experience an instantaneous
total linear acceleration of 1 m/sˆ2.
10. A True
B False
⊲ Containers A,B and C are filled to the same level
with water. The pressure at the bottom of container
C equals the pressure at the bottoms of A and B.
11. A True
B False
⊲ The center of gravity of an object must be physically located
somewhere within the material that makes up the object.
12. A True
B False
⊲ An astronaut orbiting the earth in the Spacelab steps on a
scale mounted to the floor. His weight registers as zero.
13. A True
B False
⊲ An astronaut orbiting the earth in the Spacelab experiences
zero acceleration.
14. A True
B False
⊲ A 2 lb. block on the earth weighs more than a 2 lb. block
on the moon.
15. A True
B False
⊲ Two isolated objects moving on a flat frictionless surface
collide elastically. The sum of the momenta after the collision
is the same as it was before the collision.
16. A True
B False
Wade Fisher - PHY231, Fall 2012 - Introductor
Exam2_Practice2
9
1 pt
The curve represents an object in simple harmonic motion.
Match the points on the curve to the velocity and acceleration
of the object.
⊲ The velocity is zero, and the acceleration is negative.
17. A Point A
B Point B
C Point C
D Point D
E Point E
F Point F
G Point G
H Point H
⊲ The velocity is negative, and the acceleration is negative.
18. A Point A
B Point B
C Point C
D Point D
E Point E
F Point F
G Point G
H Point H
⊲ The velocity is positive, and the acceleration is positive.
19. A Point A
B Point B
C Point C
D Point D
E Point E
F Point F
G Point G
H Point H
⊲ The velocity is negative, and the acceleration is positive.
20. A Point A
B Point B
C Point C
D Point D
E Point E
F Point F
G Point G
H Point H
Wade Fisher - PHY231, Fall 2012 - Introductor
Exam2_Practice2
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