Question

Sung rolls a marble off the edge of a table. She rolls the marble off the same table again but at a different speed.

Which best describes the projectile motion of the marble as it leaves the table at the two different speeds?

The marble’s horizontal and vertical velocities change.
The marble’s horizontal and vertical velocities remain the same.
The marble’s vertical velocity changes, but its horizontal velocity does not.
The marble’s horizontal velocity changes, but its vertical velocity does not.

Answer 1

The marble’s vertical velocity changes, but its horizontal velocity does not.

Explanation: gravity accelerates the marble downward so its vertical speed changes during the fall, while (neglecting air resistance) there is no horizontal acceleration so the horizontal speed stays constant.