Every mother like yours think & wish that her children
Do not waste time & always get good grades in the study
So she is rite.
You can find some other hobbies like playing, painting ,gardening .
Reading story books . But ask your mom that she should
Allow you at least one hour for computer as well .
b/c this is modern tool & you should get expert of it .
in future you will have to use it a lot.
but promise that you will give one hour daily & on weekend 2 hours .
i hope she will agree to it.