Which of these best explains why the coin fell straight down into the cup instead of remaining on the index card? F. The coin was at rest until the card was removed, so it tended to remain in the same location. Once the card was gone, the unbalanced force of gravity caused the coin to fall.

G. Moving the card applied an action force on the coin. Since the card was gone, gravity applied a reaction force on the coin.

H. The card had less mass than the coin, so a smaller force of gravity acted on the card. The larger force of gravity on the coin made it fall.

J. The acceleration of the coin falling into the cup was equal and opposite to the acceleration of the card.