It will depend on the type of window and the speed of the tennis ball. Professional tennis players can serve from 120-150 mph. Windows are broken for wind speed of over 75mph. So with that speed (120-150 mph), a tennis ball could really break a window.
Are you a new tennis player and just starting to learn the game? Then there will be a lot of new challenges for you. Check out some tennis tips from the Pros here.
In tennis news, Serena Williams put the disappointment of Paris behind her, showing little mercy in a 6-1 6-2 demolition of compatriot Anna Tatishvili in the first round at Wimbledon. Find out more at Thestar.com.