What happens after the caliper piston squeezes the brake pad?

When the caliper piston squeezes the brake pad, it causes the brake pad to make contact with the rotor. This creates friction between the rotor and the brake pad, which is essential for slowing down or stopping the vehicle. The friction generated is what ultimately translates the kinetic energy of the moving vehicle into heat, thereby reducing speed and bringing the vehicle to a halt.

The other choices are less relevant to the direct effect of the caliper piston squeezing the brake pad. For example, while hydraulic pressure is a crucial element in the brake system, it does not drop as a direct consequence of the caliper piston movement; instead, pressure is utilized to activate the braking action. Similarly, the adjuster and drum operation pertain to different braking systems, specifically drum brakes, and do not occur in the context of a disc brake system, where the caliper is located. The primary role of the caliper piston in this scenario focuses directly on the friction produced which stops the vehicle.