As a helium-filled balloon rises in the air, it becomes
A) bigger.
B) more dense.
C) heavier.
D) all of the above
E) none of the above
Answer: A
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The Moon has no sustained atmosphere. What advantages would you have if you built an observatory on the lunar surface?
What will be an ideal response?
Which of these statements is true for the image formed by an object placed in front of a thin lens?
A. convex lenses never produce virtual images B. real images are always enlarged C. real images are always inverted D. virtual images are always inverted
Pluto's density is 1.8 g/cm3 . Iron is about 5 g/cm3 . Rock is about 3 g/cm3 . Ice or water is 1.0 g/cm3 . This implies that
a. Pluto has a large iron-nickel core. b. Pluto is about 35% water ice and 65% rocky material. c. Pluto is all rock. d. Pluto is all water or water ice.
According to the Hubble law, where H = 17 km/s/106 lightyears, what is the velocity of recession of a quasar at a distance of 2 billion lightyears from Earth?
a. 0.75 c b. 0.33 c c. 0.55 c d. 0.11 c e. 0.93 c