I had resized my root partition from 30gb to 70gb using gparted. But Ubuntu still shows that I have the same old disk size while gparted shows that I acually have 70gb and that the other 40gb is somehow used. How can I fix this?

Output of 'df -h':

Filesystem      Size  Used Avail Use% Mounted on

/dev/sda5        30G   16G   13G  55% /

none            4.0K     0  4.0K   0% /sys/fs/cgroup

udev            1.9G  8.0K  1.9G   1% /dev

tmpfs           391M  884K  390M   1% /run

none            5.0M     0  5.0M   0% /run/lock

none            2.0G  284K  2.0G   1% /run/shm

none            100M   48K  100M   1% /run/user

/dev/sda6       341G  115G  227G  34% /media/Data

/dev/sdb1       932G  459G  474G  50% /media/sidharth/passport

Output of mount:

/dev/sda5 on / type ext4 (rw,errors=remount-ro)

proc on /proc type proc (rw,noexec,nosuid,nodev)

sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)

none on /sys/fs/cgroup type tmpfs (rw)

none on /sys/fs/fuse/connections type fusectl (rw)

none on /sys/kernel/debug type debugfs (rw)

none on /sys/kernel/security type securityfs (rw)

udev on /dev type devtmpfs (rw,mode=0755)

devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)

tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)

none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)

none on /run/shm type tmpfs (rw,nosuid,nodev)

none on /run/user type tmpfs (rw,noexec,nosuid,nodev,size=104857600,mode=0755)

/dev/sda6 on /media/Data type fuseblk (rw,nosuid,nodev,allow_other,default_permissions,blksize=4096)

binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)

gvfsd-fuse on /run/user/sidharth/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,user=sidharth)

/dev/sdb1 on /media/sidharth/passport type fuseblk (rw,nosuid,nodev,allow_other,blksize=4096)