Question

A railroad flatcar is travelling to the right at speed of 13 m/s relative to an observer on the ground. Someone is riding a motor scooter on the flatcar. What is the velocity of motor scooter relative to the flatcar if its relative velocity to the observer on the ground is (a) 18 m/s to the right? (b) 3 m/s to the left? (c) zero?

Answer 1

Given:

$v=13\:\rm m/s$

(a)

$$u=18-13=5\:\rm m/s \quad (right)$$

(b)

$$u=18+3=21\:\rm m/s \quad (left)$$

(c)

$$u=18+0=18 \:\rm m/s \quad (left)$$