Which type of telescope did Galileo turn skyward in 1610?
A. single lens refractor
B. achromatic refractor
C. prime focus reflector
D. Newtonian reflector
E. Cassegrain reflector
Ans: A. single lens refractor
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If a spaceship travels near the speed of light away from the Earth, an observer on Earth would see the length of the spaceship ________
Fill in the blank(s) with correct word
Ammonia, NH3, boils at a higher temperature than phosphine, PH3 . This is probably due to
a. ammonia being more dense than PH3. b. ammonia having the lower formula mass. c. hydrogen bonding among the NH3 molecules. d. ammonia being ionic and phosphine being covalent.
The unstable isotope 234Th decays by ? emission with a half-life of 24.5 days. The initial decay rate of the sample was 9.9 × 1013 Bq. (1 u = 1.6605 x 10-27 kg)
(a) What mass of 234Th was initially present? (b) What is the decay rate after 68 days?
A lab specimen is 15.2 mm from a convex lens. The image is 4.0 mm tall and 9.0 cm from the lens. How tall is the specimen?
A) 6.8 mm B) 5.4 mm C) 1.7 mm D) 0.68 mm