0.10 m
0.10 m
0.10 m
Physics 2B Final 11/28/20
PHYSICS 2B EXAM (answer all questions on scantron 882-ES)
You must turn in this exam with your Scantron sheet. DUE 12/15/00 at NOON.
Assume the speed of sound in air is 340 m/s.
1. Bats use echolocation to navigate through their surroundings. The Vespertiliondae family of
bats emit short chirps as they fly. The chirps last about 0.003 seconds with a time interval of
0.070 seconds between chirps. Calculate the farthest object that can be detected by these
bats.
A. 12 m
B. 24 m
C. 36 m
D. 48 m
E. 96 m
2. Two loudspeakers radiate in phase at 170 Hz. A physics student sits 8 m from one speaker
and 12 m from the other. The intensity level from either speaker alone is 60dB. The student
measures the intensity level when both speakers are on. What will the sound meter read?
A. 0 dB
B. 60 dB
C. 63 dB
D. 66 dB
E. 69 dB
3. A stretched string of length L is observed to vibrate in five antinodes when driven by a
6.60x102 Hz mechanical vibrator. At what frequency are 3 antinodes observed?
A. 11.0x102 Hz
B. 825 Hz
C. 528 Hz
D. 396 Hz
E. 176 Hz
4. Three long parallel wires are at the corners of an equilateral triangle. The current in each wire
is 7.5A. Each side of the triangle is 0.10 m long. Assuming the upper wire is 1.0m long,
calculate the magnitude of the force on the upper wire due to the lower wires. Note: the
cross means that the current is into the page and a dot means that the current is out of
the page.
A. 1.1x10-4 N
B. 1.9x10-4 N
C. 2.2x10-4 N
D. 3.5x10-4 N
E. 6.0x10-4 N
5. Calculate the magnetic field at the upper vertex (refer to the figure of problem 6) due to the
lower wires.
A. 4.8x10-6 T
B. 1.5x10-5 T
C. 2.6x10-5 T
D. 3.0x10-5 T
E. 3.4x10-5 T
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