Describe the motion of the marble. Be sure to explain fully, addressing the relevant underlying material.

Question

A spring loaded cannon on wheels is traveling along a flat track at constant speed. It shoots a marble directly upward into the air. Describe the motion of the marble. Be sure to explain fully, addressing the relevant underlying material.

Answer 1

Hey Ghianec,

1. Maybe it helps to break this apart into horizontal and vertical. Remember that these two do not interact - motion in one direction does not affect what happens in the other direction
2. Vertically, it should be clear that the marble goes up, starts to slow down, reaches some max height, then turns and accelerates back to the ground.
3. Horizontally, objects maintain the same speed unless there's some horizontal force (like if it hits a wall, there's wind, air friction, etc. Intro physics always ignores air friction)
4. If the cannon is moving when it shoots the marble, then the marble is also moving, so it will keep moving at that same horizontal speed while it's in the air. If you've ever tried a lay-up in basketball while running at full speed, this should make sense.

Hope this helps. In the end, the marble's path will be parabolic, just like if it was shot out of a stationary cannon that was pointed at an angle.