An observer on Earth observes Planet X to be 16 light-years away and stationary. An observer in a spaceship passing Earth on its way to Planet X observes Planet X to be 9.6 light-years away. According to the observer in the spaceship, it takes years between Earth passing by and Planet X passing by. a) 10 years.
b) 12 years.
c) 14 years.
d) 16 years.
e) 18 years.

On a frictionless air track, a blue glider with mass 0.200 kg is moving to the right with a speed of 8.00 m/s. it strikes a red glider that has mass 0.600 kg and that is initially at rest. after the collision, the blue glider is moving to the left with a speed of 3.00 m/s.(a) what are the magnitude and direction of the velocity of the red glider after the collision? (b) is this collision elastic?