The measured value of the speed of light is about 300,000 km/s. Suppose a futuristic space train is traveling at 200,000 km/s with its headlights on. If you could measure the speed of the light from the headlights, you would find it to be
A) 200,000 km/s.
B) 100,000 km/s.
C) 300,000 km/s.
D) 500,000 km/s.
C
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As temperatures become large, the denominator in equation T4.41 becomes
A. very large. B. very small. C. approximately 1. D. approximately ?1
A man is moving by you at a speed close to the speed of light. Which of the following correctly summarizes the effects you would notice on his mass, size, and time?
A) His mass would be increased from its value at rest, his length would be decreased from its rest value but only in the direction in which he is moving, and his time would be running slower than yours. B) His mass would be increased from its value at rest, his length, width, and height would all be decreased no matter what direction he is moving, and his time would be running slower than yours. C) His mass would be decreased from its value at rest, his length would be decreased from its rest value but only in the direction in which he is moving, and his time would be running slower than yours. D) His mass would be increased from its value at rest, his size would be increased, and his time would be running slower than yours.
A student wishes to build a telescope. She has available an eyepiece of focal length -5.0 cm. What focal length objective is needed to obtain a magnification of 10x?
What will be an ideal response?
Three point charges are placed on the x-axis, as follows. A charge of +2.0 ?C is at the origin, a charge of -2.0 ?C is at x = 50 cm,
and a charge of +4.0 ?C is at x = 100 cm. What are the magnitude and direction of the electrostatic force on the charge at the origin due to the other two charges? (k = 1/4??0 = 9.0 × 109 N ? m2/C2 )