# Homework Help: Need Help - Physics Problems

1. Oct 10, 2004

### midnightassassinx

1) A block is placed agains the vertical front of a cart. What acceleration must the cart have in order for the block to not fall? The coefficient of static friction between the block and the cart is Us (mu s). How would an observer on the cart describe the behavior of the block? (Solve with variables)

2) A block B, with a mass Mb, rest on block A, iwth a mass of Ma, which in turn is on a horizontal tabletop. The coefficient of kinetic friction between block A and the tabletop is Uk (mu k), and the coefficient of static friction between block A and block B is Us (mu s). A massless string is attached to block A and passes over a frictionless, massless pulley and block C is suspended from the other end of the string. What is the largest mass Mc that block C can have so that blocks A and B still slide together when the system is released from rest.

2. Oct 10, 2004

### Sirus

Couple things. First, please always remember to show us what you have done in attempting a problem and where you got stuck. Second, always begin these types of problems with a free-body diagram (or several, as in question 2). Then we can help you.