Neglecting air resistance, Sammy Smarts on a high ladder releases a ball that strikes the ground with 100 J of kinetic energy. If he were to instead throw the ball straight upward, it will soon reach the ground with a kinetic energy of
A) less than 100 J.
B) 100 J.
C) more than 100 J.
Answer: B
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Polarization: A vertically polarized beam of light of intensity 100 W/m2 passes through two ideal polarizers. The transmission axis of the first polarizer makes an angle of 20.0° with the vertical, and the transmission axis of the second one makes an angle of 40.0° with the vertical. What is the intensity of the light after it has passes through both polarizers?
A. 22.2 W/m2 B. 44.4 W/m2 C. 66.6 W/m2 D. 78.0 W/m2 E. 11.7 W/m2
A boy kicks a football from ground level with an initial velocity of 20 m/s at an angle of 60° above the horizontal. What is the horizontal distance to the point where the football hits the ground?
A) 20 m B) 35 m C) 18 m D) 60 m E) 30.0 m
Graphical Addition: Two vectors, of magnitudes 20 mm and 50 mm, are added together. Which one of the following is a possible value for the magnitude of the resultant?
A. 10 mm B. 20 mm C. 40 mm D. 80 mm
The Copernican (heliocentric) model explained things better than the Ptolemaic (geocentric) model, except:
a. it did not explain the relative positions of stars as seen from Earth at different times of year. b. it did not explain why Mercury is always near the Sun. c. it was conceptually more complex than the Ptolemaic model. d. it did not explain planetary motion clearly. e. it required a great deal more mathematical calculation.