In a test of equipment the following procedure is carried out. Spacecraft ?1 is traveling at 0.75c and fires a laser pulse in the forward direction at Spacecraft ?2, which is testing its device that measures the speed of laser pulses as they pass by the spacecraft. Spacecraft ?2 is traveling at 0.95c in a direction away from Spacecraft ?1 . The device is working properly, and the speed of
the pulse as it passes is successfully measured. What is the speed of the laser pulse measured in this case?
a. 0.80c
b. 0.70c
c. c
d. This is a question that cannot be answered without knowing in which reference frames the speeds given in the problem. If you agree, then this is the answer that you should choose.
c
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In the lab, charged particles are directed toward one another, each at speed 0.500 c. What is the speed of the particles moving toward the left with respect to the particles moving to the right?
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The magnetic field going through a stationary circular loop increases from zero to 5 T in a certain time t. The induced current in the loop will depend on the radius of the loop, r, the resistance of the loop, R, and the time, t. If two of these stay constant, the induced current can be directly proportional to:
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