What is SgrA*?
A) a source of bright X-ray emission coming from the entire constellation of Sagittarius
B) a source of bright radio emission in the center of our galaxy
C) a source that is bright in the visible wavelengths in the center of our galaxy
D) the brightest star in the constellation Sagittarius
E) the bulge at the center of our galaxy
B
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Radio station KBOB broadcasts at a frequency of 85.7 MHz on your dial using radio waves that travel at 3.00 × 108 m/s
Since most of the station's audience is due south of the transmitter, the managers of KBOB don't want to waste any energy broadcasting to the east and west. They decide to build two towers, transmitting in phase at exactly the same frequency, aligned on an east-west axis. For engineering reasons, the two towers must be AT LEAST 10.0 m apart. What is the shortest distance between the towers that will eliminate all broadcast power to the east and west?
Equilibrium: As shown in the figure, a woman is straining to lift a large crate, but without success because it is too heavy. We denote the forces on the crate as follows: P is the magnitude of the upward force being exerted on the crate by the person, C is the magnitude of the vertical contact force on the crate by the floor, and W is the weight of the crate. How are the magnitudes of these forces related while the person is trying unsuccessfully to lift the crate?
A. P + C = W B. P + C < W C. P + C > W D. P = C
A CD makes one complete revolution every tenth of a second. Which has the largest linear (tangential) velocity?
A. point 1
B. point 2
C. point 3
D. point 4
The position of a particle moving along the x axis is given by x = (21 + 22t ? 6.0t2) m, where t is in s. What is the average velocity during the time interval t = 1.0 s to t = 3.0 s?
a. ?6.0 m/s b. ?4.0 m/s c. ?2.0 m/s d. ?8.0 m/s e. 8.0 m/s