Alana is skateboarding at 19 km/h and throws a tennis ball at 11 km/h to her friend Oliver who is behind her leaning against

a wall. What is the speed of the tennis ball if someone was watching the exchange on the sidewalk?

8 km/hr

11 km/hr

15 km/hr

30 km/hr

8 km/hr.

Explanation:

Its right on edgeniuty

30 km/h

Explanation:

The resultant speed since the direction is the same is found by adding the two speeds hence 19+11=30 km/h. In case the direction was different, we would subtract. Since for this case the direction is same, the resultant speed is therefore, 30 km/h. However, in case Alana is the reference, the speed would be 11 km/h