Consider two blinking warning lights 3000 m apart along a railroad track. These lights flash simultaneously in the ground frame. Let W be the event of the west light blinking, and let E be the event of the east light blinking. A train moves eastward along the track at a relativistic speed ?. Suppose an observer in the train passes the west light just as event W happens. By carefully measuring when the light from event E arrives and calculating the distance between the two lights (by observing how long it takes to travel between the lights at the known speed ?), the observer is able to infer when event E actually happened in the train frame. The observer concludes that
A. Event W happened before event E in the train frame.
B. Events W and E were simultaneous in the train frame.
C. Event E happened before event W in the train frame.
D. One cannot determine unambiguously which event occurs first in the train frame.
C. Event E happened before event W in the train frame.
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A charge of 50-?C is placed on the y axis at y = 3.0 cm and a 77-?C charge is placed on the x axis at x = 4.0 cm. If both charges are held fixed, what is the magnitude of the initial acceleration of an electron released from rest at the origin?
a. 1.2 × 10^20 m/s2 b. 1.5 × 10^20 m/s2 c. 1.0 × 10^20 m/s2 d. 1.8 × 10^20 m/s2 e. 2.0 × 10^20 m/s2
A brass plate measures 30.0 cm by 40.0 cm. The coefficient of linear thermal expansion is 
If the temperature of the plate is increased by 10.0 K, then what is the increase in the area of the plate?
A. 0.350 cm2 B. 0.404 cm2 C. 0.456 cm2 D. 0.502 cm2 E. 0.555%
If we found a solar system where the central star's mass was double that of the Sun, what would be the period a planet orbiting 1 AU from the central star?
A) more than a year B) less than a year C) about a year D) impossible to say, since we need to know the mass of the planet to predict its period
The initial prediction by Percival Lowell of Pluto's position was close to the place it was, in fact, found by Clyde Tombaugh in 1930
Indicate whether the statement is true or false