The star Vega has an apparent visual magnitude of 0.03 and the star HR 4374 has an apparent visual magnitude of 4.87 . It has been determined that both stars are at the same distance from Earth. What does this information tell us about the two stars?
a. Vega must be closer to Earth than HR 4374.
b. Vega must be farther from Earth than HR 4374.
c. Vega must produce less energy/second than HR 4374.
d. Vega must produce more energy/second than HR 4374.
e. Vega will appear fainter to us than HR 4374.
D
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Rotational Kinetic Energy: A uniform solid disk is released from rest and rolls without slipping down an inclined plane that makes an angle of 25° with the horizontal. What is the forward speed of the disk after it has rolled 3.0 m, measured along the plane?
A. 2.0 m/s B. 3.5 m/s C. 4.1 m/s D. 5.7 m/s E. 6.3 m/s
Which situation has the least magnitude of angular momentum about the origin?
A. A 2 kg mass travels along the line y = 3 m with speed 1.5 m/s. B. A 1 kg mass travels in a circle of r = 4.5 m about the origin with speed 2 m/s. C. A disk with I = 3 kg·m2 rotates about its center (on origin) with ? = 3 rad/s.
1.A 2.B 3.C 4.Both A and B 5.Both A and C 6.Both B and C 7.All have the same magnitude angular momentumThe Sun rotates ________ at its equator compared to near its poles.
A. slower B. backwards C. the same D. faster
Alternating current and voltage (AC), rather than direct current and voltage (DC), are used for domestic electrical power. The reason for this is based on one of the following physical principles. Which one?
A) When a current flows through a resistance, heat is generated. B) When a current flows through a wire, a magnetic field is created. C) When the number of magnetic field lines passing through a circuit changes, a voltage is generated in the circuit. D) When a current-carrying wire is placed in a magnetic field, it may experience a force if properly oriented. E) Opposite electric charges attract each other, and like charges repel each other.