You drop a stone down a well that is 9.5 m deep. How long is it before you hear the splash? The speed of sound in air is 343 m/s and air resistance is negligible
A) 1.2 s B) 1.4 s C) 1.3 s D) 1.6 s E) 1.5 s
B
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The orbits of Population II stars have been compared to:
A) planets around the Sun. B) satellites around planets. C) comets around the Sun. D) binary stars. E) the accretion disk around a black hole.
An ideal solenoid of radius a has n turns per unit length and current I. The magnetic flux ?B through any circular area of radius a inside the solenoid, centered on and perpendicular to the solenoid axis, is
A.
.B.
.C.
D.
E.
You throw a ball up in the air and hold your hand under it to catch it when it comes down. The reason why the ball stops is because
a. your hand is there: your hand exerts no force on the ball. b. your hand exerts a force on the ball perpendicular to its velocity. c. your hand exerts a force on the ball in the direction of its velocity. d. your hand exerts a force on the ball in the direction opposite to its velocity. e. your hand and the ball exert forces in the same direction on each other.
Coulomb's Law: As shown in the figure, three charges are at corners of a rectangle. The charge in the bottom right corner is Q = - 90 nC, and all the other quantities are accurate to two significant figures. What is the magnitude of the net electrical force on Q due to the other two charges? (k = 1/4??0 = 9.0 × 109 N ? m2/C2) 
A. 3.8 × 10-2 N B. 2.8 × 10-2 N C. 5.3 × 10-2 N D. 7.1 × 10-2 N