simon is riding a bike at 12 km/h away from his friend keesha. he throws a ball at 5 km/h back to keesha…

simon is riding a bike at 12 km/h away from his friend keesha. he throws a ball at 5 km/h back to keesha, who is standing still on a sidewalk. how fast would keesha say the ball is traveling? 5 km/h 7 km/h 12 km/h 17 km/h

simon is riding a bike at 12 km/h away from his friend keesha. he throws a ball at 5 km/h back to keesha, who is standing still on a sidewalk. how fast would keesha say the ball is traveling? 5 km/h 7 km/h 12 km/h 17 km/h

Answer

Explanation:

Step1: Analyze relative - motion

Simon is moving away at 12 km/h and throws the ball back at 5 km/h. The relative velocity of the ball with respect to Keesha is the difference between Simon's velocity and the ball - throwing velocity. Let Simon's velocity be (v_{s}=12\ km/h) (away from Keesha) and the ball's velocity with respect to Simon be (v_{b/s}=- 5\ km/h) (towards Keesha). The velocity of the ball with respect to Keesha (v_{b}) is given by (v_{b}=v_{s}+v_{b/s}).

Step2: Calculate the velocity

(v_{b}=12+( - 5)=7\ km/h)

Answer:

7 km/h