Sonar is used to determine the speed of an object. A 40.0-kHz signal is sent out, and a 42.0-kHz signal is returned. If the speed of sound is 345 m/s, how fast is the object moving?
A) 6.9 m/s
B) 8.4 m/s
C) 331 m/s
D) 347 m/s
B
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Earth's atmosphere is most transparent to all wavelengths of ________ light.
A) infrared B) visible C) ultraviolet D) x-ray E) both visible and ultraviolet
A cast iron pipe (L 5 12 m, weight density 5 72 kN/m3, d2 5 100 mm, and d1 5 75 mm) is lifted by a hoist. The lift points are 6 m apart. The maximum bending stress in the pipe is approximately:
(A) 28 MPa
(B) 33 MPa
(C) 47 MPa
(D) 59 MPa
Two nonparallel vectors determine a plane. Relative to the plane determined by the position vector where the force is applied and the force vector, in which direction is the torque vector about the origin?
A) perpendicular to the plane B) in the plane, but perpendicular to both the position vector and the velocity vector C) in the plane, but perpendicular to the velocity vector D) in a direction dependent on the magnitudes of the velocity and position vectors E) in the plane, but perpendicular to the position vector
A proton that is initially at rest is accelerated through an electric potential difference of magnitude 500 V. What speed does the proton gain? (e = 1.60 × 10-19 C , mproton = 1.67 × 10-27 kg)
A) 2.2 × 105 m/s B) 1.1 × 105 m/s C) 9.6 × 105 m/s D) 3.1 × 105 m/s