Final answer:
If two objects move towards each other at the same speed, they will collide; the collision could result in various final velocities depending on the collision's elasticity and mass distribution.
The coefficient of kinetic friction between two moving surfaces is typically independent of their relative speed.
Step-by-step explanation:
If two objects are moving towards each other at the same speed, the outcome would be a) They collide. This is because if two objects are moving toward each other along the same line, their relative speed is the sum of their individual speeds.
Upon collision, depending on the type of collision (elastic or inelastic), the final velocities of the masses after the collision may vary.
If the collision is perfectly inelastic, they might stick together and move with a common velocity or stop if their masses are equal and the speeds are identical. If the collision is perfectly elastic and the masses are equal, they essentially exchange velocities.
For instance, when two objects of equal mass collide and one is initially at rest, the moving object may come to rest after the collision while the previously stationary object may move away with the initial velocity of the first object, in accordance with the conservation of momentum.
In this case, momentum is conserved, but kinetic energy is not necessarily conserved unless the collision is perfectly elastic.
Regarding two surfaces in contact moving past each other, as the relative speed between the two surfaces increases, the magnitude of their coefficient of kinetic friction typically remains constant and is independent of the relative motion.