The first hand in the air makes the second and third ones easier. Be the first hand.

Groups wait for a precedent before anyone moves, and the first person supplies it. What looks like a room of reluctant people is a room of people who needed someone to establish that this is a thing one does here. After the first hand, the cost of the second drops to almost nothing.

In the next meeting or class where a question hangs unanswered, put your hand up before you have polished the wording. You are not only asking; you are opening the floor. Watch how quickly others follow once the silence has been broken for them.