5. A train 280 meters long travels at a speed of 18 meters per second across a bridge. It takes 20 seconds from the moment the tail of the train gets on the bridge until the head of the train leaves the bridge. Therefore, the length of the bridge is $\qquad$ _.
Analysis: The distance from the rear of the car reaching the bridge to the front of the car leaving the bridge $=$ Bridge length - Car length $=20 \times 18=360$ (meters), then the bridge length $=360+$ Car length $=360+280=640$ (meters)