A railroad flatcar is traveling to the right at a speed of 13.0 m/s relative to an observer standing on the ground. Someone is riding a motor scooter on the flatcar (Fig. E3.30). What is the velocity (magnitude and direction) of the scooter relative to the flatcar if the scooter's velocity relative to the observer on the ground is (a) 18.0 m/s to the right?

Question

A person rides a scooter on a flatcar moving right, while an observer watches from the ground.

Accepted Answer

Hi, everyone. Let's get started. So during filming for an action movie, Leo was running on top of a train that is moving due east at a speed of 16 m per second relative to the director who is standing on the side of the rail tracks. What is the velocity of Leo relative to the train? If Leo's velocity relative to the director standing on the side of the railroad tracks is 3.7 m per second due east. So we have two different velocities here. We have the velocity of Leo from the perspective of the director running three point seven meters per second, But he's on top of a train that's also moving. And the director sees the train moving at meters per second and we need to determine the velocity of Leo relative to the train. So in order to do that, we can actually because our two values here are both from the same perspective of the director, we can actually subtract those. And if you recall the velocity of Leo relative to the train would then be equal to 3.7 meters per second. That's Leo's velocity minus the velocity of the train 16 m/s. And that will give you a value of negative 12.3 meters per second. So if we scroll down to our answer choices here, we can see that answer choice to be negative 12.3 m/s is the correct answer. Thank you.

Verified Solution

Key Concepts

Relative Velocity

Frame of Reference

Vector Addition