1. The problem statement, all variables and given/known data What three gravitational forces act on the oceans of the earth to cause the tides? 3. The attempt at a solution Hi. I was wondering if anyone could help me with this question. Everyone knows it is the gravitational force of the moon, but that's about it. Could the gravitational force of the earth and of the sun also be involved? But then why not add Mars and all the other planets, as they exert a force too, more or less. I also found answers such as the gravitational force of the moon, the sun and inertia or earth's rotation but that's not a gravitational force. Thank you.