In the proton-proton cycle, two positrons are produced. What more familiar particles are they similar to, and how do they differ?
What will be an ideal response?
Positrons are anti-electrons, made of antimatter, and with a positive charge instead of the negative charge of normal electrons.
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The Crab Nebula is the remnant of ____
a. the SN1987a supernova b. a supernova which triggered a mass extinction on Earth c. a supernova recorded by Chinese astronomers d. a supernova which triggered the formation of the Sun e. a supernova in the Large Magellanic cloud
Before the switch is closed in the figure, the potential across the capacitor is 200 V. At some instant after the switch is closed, the instantaneous current is 0.70 A. What is the energy in the capacitor at this instant?
A. 49 mJ B. 31 mJ C. 80 mJ D. 0.13 J E. 62 mJ
Which of the following describes an object that is moving with an unchanging speed but a changing velocity?
A) A car slowing down while moving along a straight line. B) A car rounding a curve at a steady 80 km/hr. C) A car moving along a straight horizontal (level) line at a steady 80 km/hr. D) A car moving up a straight hill [a hill whose "slope" is unchanging] at a steady 80 km/hr, when the car is midway up the hill. E) Both answers C and D are correct.
Mt. Everest is more than 8 000 m high. How fast would an object be moving if it could free fall to sea level after being released from an 8 000-m elevation? (Ignore air resistance.)
a. 396 m/s b. 120 m/s c. 1 200 m/s d. 12 000 m/s