A car suspension has two jobs that fight each other: keep the tires in useful contact with the road while isolating the body from bumps and wheel motion.

The spring and damper do different physics:

• A spring stores and returns energy. For an ideal linear spring, F=-kx.
• A damper/shock absorber dissipates motion energy as heat; a simplified model has damping force roughly proportional to suspension velocity, F≈-cv.

Without damping, a sprung car would continue oscillating after a bump. Without springs, road impacts would be transmitted brutally into the body.

The wheel, tire, brake, hub, and some suspension parts form unsprung mass. Lower unsprung mass generally helps the tire follow rapid road changes because less mass has to accelerate vertically.

Geometry also matters. Control arms, struts, links, and bushings determine how camber, toe, caster, and track change as the wheel moves. This is why “suspension” is not merely springs and shocks.

Big idea: Good suspension is controlled relative motion: let the wheel move rapidly enough to follow the road while keeping the body comparatively calm.

An anti-roll bar links left and right suspension movement and resists body roll in corners, but stronger roll stiffness can also change grip balance between the axles.