Friction is the resistance to motion that occurs when one material slides across another material. all materials have surface irregularities and are not perfectly smooth.

as the materials move, the irregularities get caught on one another requiring more force. friction wears down a surface while producing heat, such as tires on a road or skin receiving a rug burn from sliding across carpet.

1. why would someone rub their hands together really fast when they are cold?

2. give another example of friction that was not discussed above.

May someone explain how to do this question?

On a horizontal frictionless surface, a small block with mass 0.200 kg has a collision with a block of mass 0.400 kg. immediately after the collision, the 0.200 kg block is moving at 12.0 m/s in the direction 30° north of east and the 0.400 kg block is moving at 11.2 m/s in the direction 53.1° south of east. use coordinates where the +x-axis is east and the +y-axis is north.(a) what is the total kinetic energy of the two blocks after the collision (in ) what is the x-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your ) what is the y-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your answer.)

Does current flow through or across a resistor?