We cannot see tidal forces or tidal heating; rather, we predict that they must occur based on the orbital characteristics of the moons. what observational evidence confirms that tidal heating is important on io?

When considering gravity acceleration and the force of acceleration, what must be true? a. the direction of acceleration must be perpendicular to the direction of the force. b. the direction of the force and the direction of acceleration must be the same as each other. c. the direction of the force and the direction of acceleration must be opposite of each other. d. the mass of the body must be the same as the acceleration of the body.