# Friction mass physics

1. Dec 15, 2005

### Omar.Castillo

A brick of mass 50 g is placed on a level floor inside a moving train. The dimensions of the brick is 10cm*8.0cm*6.0cm. It is placed with one of its 10cm*6cm faces on the floor so that the 6.0 cm edges are parallel to the direction of motion. The train is braked suddenly. Assume that the floor is rough enough to prevent sliding, but allow the brick to topple about a 10cm edge. Find the minimum couple required to makethe brick topple about the 10 cm edge?

I know that the coefficient of static friction is proportional to the normal force. So must I equal the normal force to the coefficient of kinetic friction to get the answer?

After that question the next one is to find the minimum decelaration of the train that makes the brick topple about the 10 cm edge. and determine the minimum value of the coefficient of static friction between the brick and the floor that prevents the sliding

2. Dec 15, 2005

### Omar.Castillo

I cannot imagine how to get the torque force without using fictional forces any way to get it without it?

3. Dec 15, 2005

### Omar.Castillo

Got it

Never mind guys I finally got it after hard 3 hour work, thx anyway for at least looking at it

4. Dec 15, 2005

### lightgrav

All you do is identify the axis of rotation (the front edge!)
and sum the torques around that axis.