Question

While skateboarding at 19 km/h, Alana throws a tennis ball at 11 km/h to her friend Oliver. If Alana is the reference frame,

the speed of the tennis ball is
km/h

Answer 1

Speed, v = 30 km/h

Step-by-step explanation:

It is given that,

Speed while skateboarding, v₁ = 19 km/h

Speed with which tennis ball is thrown, v₂ = 11 km/h

We have to find the speed of the tennis ball from the Alana's frame of reference.

v = v₁ +v₂

v = 19 km/h + 11 km/h

v = 30 km/h

Hence, this is the required solution.

Answer 2

11 km/hr

Step-by-step explanation:

Taking Alana as the reference frame, we consider the speed with which the ball gets away from her. Therefore the speed given will be with respect to Alana. In this case we disregard the 19 km/hr as it is common to both Alana and the ball.