- #1
esha
- 74
- 3
A card kept on a glass with a penny is jerked. The coin falls in the glass while the card moves away. why is that?
My attempt at an explanation
A force acts on the card which is greater than the static friction acting between the card and the coin. Hence the coin is able to overcome that. As the cardboard slips under it a relative motion occurs which is resisted by the kinetic friction. Since the coin has no other force acting in that direction it moves in the direction of the kinetic friction. So the coin falls back in the glass. Am i correct?
My doubts
1) If this is the case then why do we tend to use a heavier coin? If we do so then the coin would cause more static friction which can make the cardboard and the coin fly off together. This wud result into the coin not falling in the glass.
My attempt at an explanation
A force acts on the card which is greater than the static friction acting between the card and the coin. Hence the coin is able to overcome that. As the cardboard slips under it a relative motion occurs which is resisted by the kinetic friction. Since the coin has no other force acting in that direction it moves in the direction of the kinetic friction. So the coin falls back in the glass. Am i correct?
My doubts
1) If this is the case then why do we tend to use a heavier coin? If we do so then the coin would cause more static friction which can make the cardboard and the coin fly off together. This wud result into the coin not falling in the glass.