A spaceship, moving away from the Earth at a speed of 0.9c, fires a light beam backward. An observer on Earth would see the light arriving at a speed of
A. 0.1c.
B. 1.9c.
C. more than 0.1c but less than c.
D. c.
E. more than c but less than 1.9c.
Answer: D
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Coulomb's Law: A point charge Q = -12 ?C, and two other charges q2 and q2, are placed on x-y axes as shown in the figure. The electric force components on charge Q are Fx = +0.005 N and Fy = -0.003 N. (k = 1/4??0 = 9.0 × 109 N ? m2/C2, e = 1.6 × 10-19 .C(a) How many excess electrons are there in charge Q?(b) What are the charges q1 and q2, including their signs?
What will be an ideal response?
What is the most compelling piece of evidence that suggests that the dinosaurs were made extinct by the impact of an asteroid 65 million years ago?
A) a layer of sediment laid down at that time which is littered with dinosaur fossils B) dinosaur fossils are found in rock layers older than 65 million years but not younger than 65 million years C) a layer of sediment laid down at that time which is rich in the element Iridium (Ir), an element common in asteroids but less common on the Earth D) the crater from this impact can still be seen in the deserts of Arizona
A projectile is launched with initial velocity v0 at an angle of 30° above the horizontal. If a second projectile is launched with the same initial velocity but at angle of 60° above the horizontal
A) The range of the second projectile will be twice that of the first. B) The range of the second projectile will be 1.41 that of the first. C) The range of the second projectile will be one-half that of the first. D) The ranges of the two projectiles will be identical. E) It is impossible to compare the ranges of the two projectiles.
Astronaut Mark Uri is space-traveling from planet X to planet Y at a speed of 0.65c relative to the planets, which are at rest relative to each other
When he is precisely halfway between the planets, a distance of 1.0 light-hour from each one as measured in the planet frame, nuclear devices are detonated on both planets. The explosions are simultaneous in Mark's frame. What is the difference in the time of arrival of the flashes from the explosions as observed by Mark? A) 0 min B) 180 min C) 90 min D) 360 min E) 113 min