A concave mirror has a focal length of 20 cm. What is the position (in cm) of the object if the image is upright and is two times larger than the object?
a. 30
b. 20
c. 10
d. 40
e. 60
C
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A system of 3 masses is located as follows: m1 = m0 at (0, L), m2 = 2m0 at the origin, and m3 = 3m0 at (3L, 0). Where is the center of mass of these masses
A. L/6, 3L/2 B. 5L/6, 3L/2 C. 2L/13, 5L/6 D. 3L/2, L/6
Energy Levels: A hydrogen atom is excited to the n = 9 level. Its decay to the n = 6 level detected in a photographic plate. What is the frequency of the light photographed? (1 eV = 1.60 × 10-19 J, h = 6.626 × 10-34 J ? s)
A. 5.08 × 1013 Hz B. 5910 Hz C. 5910 nm D. 3.28 × 10-9 km
Starting from rest, an electron accelerates through a potential difference of 67 V. What is its de Broglie wavelength? (h = 6.63 × 10^-34 J×s, me = 9.11 × 10^-31 kg, and 1 eV = 1.60 × 10^-19 J)
a. 1.1 × 10^-10 m c. 1.9 × 10^-10 m b. 1.5 × 10^-10 m d. 2.3 × 10^-10 m
When Jim and Rob ride bicycles, Jim can only accelerate at three quarters the acceleration of Rob. Both start from rest at the bottom of a long straight road with constant upward slope. If Rob takes 5.0 minutes to reach the top, how much earlier should Jim start to reach the top at the same time as Rob?
a. 25 s b. 40 s c. 46 s d. 55 s e. 75 s