How do we measure stellar masses?
A) We measure their apparent brightness and distance (from parallax).
B) We don't really know: stellar masses are based on an informed guess.
C) We measure the orbital periods and velocities of stars in binary systems.
D) We measure their density and radius.
C) We measure the orbital periods and velocities of stars in binary systems.
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Answer the following statement true (T) or false (F)
Which of the following statements best describes the relationship between the energy EA required to increase a 1000-kg car’s speed from 0 to 23 m/s (about 50 mi/h) and the energy EB required to increase the temperature of 1 gal (? 3.8 kg) of lemonade from refrigerator temperature (about 5°C) to room temperature?
A. EA >> EB B. EA ? EB C. EA << EB
A car drives over a hilltop that has a radius of curvature 0.120 km at the top of the hill. At what speed would the car be traveling when it tires just barely lose contact with the road when the car is at the top of the hill?
A) 45.5 m/s B) 41.8 m/s C) 34.3 m/s D) 22.2 m/s E) 27.6 m/s
An electron moves in a region where the magnetic field is uniform, has a magnitude of 60 ?T, and points in the positive x direction. At t = 0 the electron has a velocity that has an x component of 30 km/s, a y component of 40 km/s, and a z component of zero. What is the pitch of the resulting helical path?
A. 13 mm B. 32 mm C. 24 mm D. 18 mm E. 3.8 mm