alana is skateboarding at 19 km/h and throws a tennis ball at 11 km/h to her friend oliver who is behind her…
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?\n8 km/hr\n11 km/hr\n15 km/hr\n30 km/hr
Answer
Explanation:
Step1: Identify velocities
Alana's velocity $v_{Alana}=19$ km/h and ball - throwing velocity $v_{ball - relative}=11$ km/h.
Step2: Use relative - velocity formula
Since the ball is thrown in the direction of Alana's motion, the velocity of the ball with respect to a stationary observer on the sidewalk $v$ is the sum of Alana's velocity and the velocity of the ball relative to Alana. So $v = v_{Alana}+v_{ball - relative}$.
Step3: Calculate the velocity
$v=19 + 11=30$ km/h.
Answer:
30 km/h