FRICTION FORCE

•At first we thought that the different bodies moving on the same substrate in different ways. •We decided to check it out. •So we hired a dad to us cut timber and supply reel.

In the big board We screw reel. In a small timber to knock one or two screws.

We did it, ready for action.

Students are changing the mass of the body and noticed by association with the force of friction.

Students are changing the type of substrate and the observed friction force.

Our snacks also can be used to demonstrate Newton's second law.

You should try.It's fun .

•Sanja Bulat teacher and students

from elementary school Branislav Nušić, Belgrade .