The stiffness of a coil is determined by its spring constant, or stiffness constant, which is denoted as k. When a coil is cut into two halves, the stiffness of the cut coils will change.
Since stiffness is directly proportional to the spring constant, we can conclude that the stiffness of the cut coils will be different from the original coil.
To determine the exact change in stiffness, we need to consider the arrangement of the cut coils. If the coil is cut in half and the two halves are arranged in series, the effective stiffness of the system will be half of the original stiffness. This is because the total stiffness is the sum of the individual stiffness values.
On the other hand, if the coil is cut in half and the two halves are arranged in parallel, the effective stiffness of the system will be double the original stiffness. In this case, the stiffness of each half adds up.
Therefore, the correct answer to the given question is (c) double.
In summary, when a coil is cut into two halves, the stiffness of the cut coils depends on their arrangement. If the halves are arranged in series, the stiffness will be half of the original. If arranged in parallel, the stiffness will be double the original.