How a 10GB network can copy 1TB data in 2 hours?
You have just done the calculation with the raw data to be transferred and not taken into account of the overhead of transferring data using networking protocols across any particular  network. Almost no networking technology transfers data without an overhead because there is the need for addressing the data, routing the data, dealing with the reliability of the network and so forth.
If we assume a layered packet-switching protocol network, such as the internet, we have many layers, each with its own overhead. Each overhead adds more bytes to the data to be transferred.
Physical Layer Overhead
 Datalink Layer Overhead
 Network Layer Overhead (IP)
 Transport Layer Overhead (TCP)
 Application Layer Overhead
 The file
 The data










Getting a large amount of data from one place to another reliabily on a packet-switching network has quite a large overhead.