Ingrid is participating in a relay race. while jogging at 9 km/h, she tosses a relay stick at 16 km/h to her teammate, who is standing still. how fast is the relay stick moving relative to ingrid?

16 km/h

Ingrid is jogging at a speed of 9 km/h. She passes the relay stick to her team and tosses the stick at 16 km/h. In Ingrid's frame of reference, speed of relay stick is 16 km/h because, she is at rest in her own reference frame. so, relative to Ingrid, speed of relay stick is 16 km/h.

If we were asked to find the speed of relay stick relative to her teammate, then the speed of Ingrid would have been added to the speed of tossing the stick.