A 40-g dart rests against a spring that has been compressed 0.06 meters. (a) If 1.12 J of work is required to compress the spring, what is the spring constant of the spring

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

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the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.