Physics 201 MWF10:20 Fall 1999 (Ford)
Final Exam Chapts. 1--17 in Cutnell and Johnson 4th ed
Conceptual multiple choice questions. Circle the correct answer.
(2 pts) 1. You are standing in the middle of the road and a car is approaching you at a speed of 20 m/s. The car's horn is emitting sound waves with a frequency of 400 Hz. The frequency of the sound waves you receive is
a) 400 Hz
b) larger than 400 Hz
c) smaller than 400 Hz
(2 pts) 2. The sound intensity level 
1 of a sound is 40 dB when the intensity is I1. If the intensity is tripled, to I2 = 3I1, by how much is the sound intensity level increased? That is, if 2 is the sound intensity level for intensity I2, what is 2 - 1?
a) 40 dB
b) 80 dB
c) 3.0 dB
d) 4.8 dB
(2 pts) 3. The fundamental standing wave frequency for sound waves in a tube open at one and closed at the other is 30 Hz. The next higher standing frequency for this tube is
a) 45 Hz
b) 60 Hz
c) 90 Hz
d) 120 Hz
Show all your work. Partial credit will be given if earned. Write your
answers in the blanks provided.
(12 pts) 4. The system shown in the sketch is released from rest and it is observed that the 20 kg block moves downward with an acceleration of 3.0 m/s2. The pulley is massless and frictionless.
a) While the blocks are moving, what is the tension in the rope connecting the blocks?
Ans. _____________________
b) What is the normal force exerted by the incline on the 10 kg block?
Ans. _______________________
c) What is the coefficient of kinetic friction between the 10 kg block and the incline?
Ans. _______________________
(10 pts) 5. A rock is thrown from the roof of a building. The initial velocity of the rock is 20 m/s at an angle of 37° above the horizontal. It is observed that the rock strikes the ground a horizontal distance of 50 m from the base of the building.
a) What is the height of the building?
Ans. _______________________
b) What is the magnitude of the velocity of the rock just before it strikes the ground?
Ans. ________________________
(10 pts) 6. A 5.0 kg block is attached to one end of a 4.0 m long rope and the other end of the rope is tied to a support. The block is held so the string is horizontal and released from rest. As the block swings back and forth, what is the tension in the rope when the rope is vertical?
Ans. _______________________
(10 pts) 7. A block of mss 3.0 kg is released from rest at the top of a ramp, a vertical height of 5.0 m above the bottom of the ramp. When the block reaches the bottom of the ramp its speed is 4.0 m/s. What is the work done by friction on the block as it moves from the top to the bottom of the ramp?
Ans. _______________________
(8 pts) 8. Blocks A and B are moving on a horizontal frictionless surface. Block A has mass 20 kg and initially is traveling east. Block B has mass 10 kg and is initially traveling north. The two blocks collide and stick together. After the collision the combined object is traveling at 3.0 m/s in a direction 37° north of east. What is the initial speed of each block?
Ans. A ____________________
B ________________________
(8 pts) 9. A hollow cylinder (I = MR2) is released from rest at the top of an incline, at a vertical height of 4.0 m above the bottom of the incline. As the cylinder rolls down the incline the work done on it by friction is negligible and the cylinder rolls without slipping. The cylinder has mass 5 kg and radius 0.10 m. What is the angular velocity 
of the cylinder when it reaches the bottom of the incline?
Ans. _____________________
(10 pts) 10. A uniform metal bar weighing 120 N is attached at one end to a wall by a frictionless hinge. The bar is held in a horizontal position by a cable that makes an angle of 53°, as shown. What is the tension in the cable?
Ans. ____________________
(12 pts) 11. The temperature of 4 moles of a monatomic ideal gas is increased from 200 K to 300 K. The gas constant R is R = 8.31 J/K·mol. Calculate the work done by the gas and its change in internal energy if the process is carried out
a) at constant pressure
Ans. W _____________________
U _______________________
b) at constant volume
Ans. W _____________________
U _______________________
(7 pts) 12. Transverse waves of wavelength 0.20 m, speed 500 m/s and amplitude 0.0030 m travel on a wire. What is the maximum speed of a point on the wire as the point travels up and down?
Ans. _____________________
(7 pts) 13. Two loudspeakers A and B are driven by the same amplifier so emit sound waves in phase and with the same frequency f. Speaker B is 2.0 m to the right of speaker A and point P
is 1.0 m to the right of speaker B. What is the smallest frequency for which destructive interference will occur at point P? Take the speed of sound to be 343 m/s.
Ans. ________________________