What additional information does Hannah need in order to calculate the tangential speed of the orbiting object?

To calculate the tangential speed of an orbiting object, Hannah would need to know the distance from the object to the center of the orbit (radius) and the time taken for the object to complete one full orbit. With this information, she can use the formula for tangential speed, which is tangential speed = 2πr / T, where r is the radius and T is the time taken for one orbit.