Why Does a Swinging Package on a Bus Indicate Its Speed?

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As your bus rounds a flat curve at constant speed, a package with mass 0.300kg, suspended from the luggage compartment of the bus by a string 42.0cm long, is found to hang at rest relative to the bus, with the string making an angle of 30.0o with the vertical. In this position, the package is 50.0m from the center of curvature of the curve. What is the speed of the bus?

I am having a lot of trouble visualizing this. Maybe it's the description, I don't know. Correct me if I'm wrong but is the luggage dangling on the string from the top the bus?
 

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The mass is hanging down inside the bus like a pendulum - it's moving under centrifugal force as the bus corners
 
So the length of the string is 42cm long and the distance from the floor of the bus to the package is 50cm. What does it mean when it says "found to hang at rest relative to the bus"?