Why is an iron bolt attracted to a magnet? A. When it is in a magnetic field, it becomes a temporary magnet.
B. It becomes a temporary magnet, whether or not it is in a magnetic
field.
C. It is attracted to Earth's magnetic field, which is always present.
D. When it is in a magnetic field, it becomes a permanent magnet.

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You have been hired to design a spring-launched roller coaster thatwill carry two passengers per car. the car goes up a 10-m highhill, then descends 15m to the track's lowest point. you'vedetermined that the spring can be compressed a maximum o 2.0m andthat a loaded car will have a maximum mass of 400kg. for safetyreasons, the spring constant should be 10% larger than the minimumneeded for the car to just make it over the top. a) what spring constant (k) should you specify ? b) what is the maximum speed of a 350 kg car if the spring iscompressed the full amount.