NATURAL SCIENCE 3rd TERM

FORCES AND MACHINES

1. What is a force?

2. Forces can be classified in                             or                           forces. But can also be classified in                          or                           forces.

3. Forces have many different effects on objects. Write one example of each effect:

    Example: Change of direction: If one ball is coming to me and I hit the ball with my racket the ball changes the direction.

4. If Earth is a sphere why don't people in the bottom part fall down to the Universe? Explain what it is this force and how it works.

5. What is the effect of the friction? What surfaces can produce friction? Write 3 examples of friction produced by different surfaces.

6. Is it possible that gravity and friction act at the same time? Write one example if it is possible.