Why must the camshaft turn a half the speed of the crankshaft?

The camshaft must turn at half the speed of the crankshaft to ensure proper timing of the engine's valve openings and closings in relation to the piston movement. Each cycle of the crankshaft involves two revolutions for the pistons (one for the intake stroke and one for the power stroke), while the camshaft only needs to open and close the valves once during those two revolutions. This synchronization ensures that the valves operate correctly with the pistons, optimizing engine performance and efficiency.