short bullet train trip from tokyo

at end of june, looking to do a short one day bullet train trip for 13yr old son. Any suggestions, where to go.

You could take him to the railway museum in Omiya (25 minutes from Tokyo), however, the bullet train never accelerates to high speeds until reaching Omiya:
http://www.railway-museum.jp/en/index.html

If you want to experience higher speed - I guess you want - one nearby destination is Odawara (35 minutes from Tokyo), from where you can access Hakone:
http://www.japan-guide.com/e/e5200.html