How long does it take for a 0.5 km train traveling at a speed of 60 km per hour to pass a 0.5 km tunnel.

According to the condition of the problem, the length of the train is 0.5 km, therefore, when the train approaches the tunnel, its last carriage will be at a distance of 0.5 km from the entrance to the tunnel.
The train will completely pass the tunnel when the last car of the train leaves the tunnel.
Since the length of the tunnel is 0.5 km, therefore the last car must cover the distance
0.5 + 0.5 = 1 km.
At a speed of 60 km / h, the train will cover this distance in
1: 60 = 1/60 hours = 1 minute.
Answer: 1 minute.