A child starts to build a house of cards by laying an 8.5-cm-long playing card with a mass of 0.75 g across two other playing cards: support card A and support card B.
If support card A is 2.0 cm from the end and exerts a force of 1.5"10%3 N, how distant from the end is support card B located?
Let the axis of rotation be at the point support card A comes in contact with the top card.