In order for a solar sail spacecraft to be accelerated to speeds high enough to accomplish interstellar travel in a reasonable amount of time, it would need to be started
A) from a lunar orbit where the gravity is weaker
B) close to Earth using mirrors on the surface to reflect sunlight onto the sails
C) far from the Sun so Jupiter could be used to help it on its way using a gravitational assist
D) close to the Sun where the radiation pressure is higher
D
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A narrow tube is placed vertically in a pan of water, and the water rises in the tube to 4 cm above the level of the pan. The surface tension in the liquid is lowered to one-half its original value by the addition of some soap
What happens to the height of the liquid column in the tube? A) It drops to 2 cm. B) It drops to 1 cm. C) It remains at the same height. D) It drops or rises, but the height cannot be calculated from the information given.
What is the approximate mass of a 1-cm2 column of air that extends from sea level to the top of the atmosphere?
A) 1 g B) 1 kg C) 10 kg D) 100 kg
The circuit below contains three resistors, A, B, and C, which all have equal resistances. The emf ? = 110V. Which resistor generates the most thermal energy after the switch is closed?
a.
A
b.
B
c.
C
d.
A and B
e.
All three generate equal amounts of thermal energy.
Length Contraction: Astronaut Hans leaves Earth in a spaceship traveling at a speed of 0.280c relative to the observer Brian at rest on Earth. Hans is holding a pencil at an angle of 30° with the direction of travel, as seen by Hans. What angle does the pencil make with the direction of travel, as seen by Brian on Earth?
A. 29° B. 30° C. 31° D. 33° E. 90°