The value is almost always less than one due to initial translational kinetic energy being lost to rotational kinetic energy, plastic deformation, and heat. It can be more than 1 if there is an energy gain during the collision from a chemical reaction, a reduction in rotational energy, or another internal energy decrease that contributes to the post-collision velocity.
\(\text { Coefficient of restitution }(e)=\frac{\mid \text { Relative velocity after collision } \mid}{\mid \text { Relative velocity before collision } \mid}\)

Friction is a good example of a nonconservative force. Work done against friction depends on the length of the path between the starting and ending points. Because of this dependence on path, there is no potential energy associated with nonconservative forces.

Spring constant is defined as the restoring force per unit displacement. Thus, it is measured in Nm^–1.

No that is not the case. Lets say a body is moving very fast but going with uniform motion so its acceleration will be zero and when acceleration is zero force is also zero so as a result W = 0 as W = F x d

In physics, circular motion is a movement of an object along the circumference of a circle or rotation along a circular path. It can be uniform, with constant angular rate of rotation and constant speed, or non-uniform with a changing rate of rotation. The rotation around a fixed axis of a three-dimensional body involves circular motion of its parts. The equations of motion describe the movement of the center of mass of a body.