A book slides slowly off a tilted table. Its speed remains constant until it finally falls off the edge. While it's sliding down the table, the book doesn't accelerate because
A. sliding friction is exerting an uphill force on it that exactly balances the downhill force due to gravity.
B. the table's support force exactly balances gravity and there are no other forces on the book.
C. momentum is a conserved quantity, so the book's momentum can't change.
D. angular momentum is a conserved quantity, so the book's angular momentum can't change.
Answer:A
A book slides slowly off a tilted table. Its speed remains constant until it finally falls off the edge. While it's sliding down the table, the book doesn't accelerate because
A. sliding friction is exerting an uphill force on it that exactly balances the downhill force due to gravity. B. the table's support force exactly balances gravity and there are no other forces on the book. C. momentum is a conserved quantity, so the book's momentum can't change. D. angular momentum is a conserved quantity, so the book's angular momentum can't change.