A policeman in a stationary car measures the speed of approaching cars by means of an ultrasonic device that emits a sound with a frequency of 41.2 kHz.
A car is approaching him at a speed of 33.0 m/s. The wave is reflected by the car and interferes with the emitted sound producing beats. What is the frequency of the beats? The speed of sound in air is 330 m/s.
A)
9.2 kHz
B)
4.1 kHz
C)
4.6 kHz
D)
1.2 kHz
E)
8.2 kHz
Question 2
A steel sphere with a radius of 2.0 m falls off a ship and sinks to a depth where the pressure is 15 MN/m2. The bulk modulus for steel is 1.61011 N/m2. What is the change in the radius of the sphere?
A)
0.021 mm
B)
4.2 mm
C)
0.42 mm
D)
0.19 mm
E)
0.063 mm
J. M. W. Turner, Rain, Steam, and Speed—The Great Western Railway.
J. M. W. Turner, Rain, Steam, and Speed—The Great Western Railway.
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